Whiskey Verdigris

A search for something to help a blog reader prompted me to take a trip back through the databases. More and more literature is digitized every year or has its copyright expired.

This paper on Whiskey Verdigris was a fun one for me because I love looks at distillation phenomena that are seldom explored. If you encountered a still puking verdigris as a first time distiller it may be a ‘wtf?, that’s not in the text books!’, but it is a phenomenon understood to be normal by experienced commercial scale distillers. My very first explanation of the phenomenon was back in 2014, A Still Operation Phenomenon Explained.

The paper is from 1937 and the experiments were conducted down in Kentucky from a sample of whiskey verdigris secured for the authors by a former University of Kentucky alum. This is all pre chromatography era so they explore and torture their sample MacGyver style to elucidate what the hell it is and how the hell it got there.

Copper is reactive and distillation is all about concentration so waves of reactive compounds move through the still. The end of a spirits run also has a unique relationship with the beginning of the next as we learned in Demisting and the Spirits Safe. Stuff at the end of the run, distilling primarily with water vapor (but not necessarily water soluble), has a tendency to be sticky. This stuff often gets stuck in the condenser, affixing to the copper, but is liberated by the next run where it is soluble in the very high alcohol content of the heads fraction. Chemical reactions happen with the copper producing a colored patina that takes the name whiskey verdigris though it is chemically different from the classic verdigris of the decorative arts (but no less beautiful!). Another strange phenomenon can also come along depending on how a distillery preps its beer (they usually try to avoid this). If the beer has not been de-gassed and liberated of its CO2, as it heats, it will have a tendency to belch. The liberated CO2 has both a corrosive action and a force that can scour the inside of the still and puke out whiskey verdigris. If you have this going on you may want to figure out how to de-gas your beer because the raw copper revealed can negatively impact your flavor.

The short paper is worth a read. These chemists were brilliant and it is fun to try and keep up with an understanding of what the hell they are doing. Among the many parts of their experiment, they are making whiskey soap and getting to smell isolated fractions that few of us will ever get to experience. Wonderful stuff.

If you have some, either send in a photo or mail me a canning jar of the stuff. I will turn it into paint and create a neo-pointalist self portrait.

As the concentration of alcohol falls in the doubler a white, insoluble, fatlike material appears in the trial box. Although most of this goes back into the singling tank, some collects in the condenser and is partially dissolved and washed out by the higher alcoholic content of the next distillation. This appears in the heads or foreshots of the next distillation and is colored a distinct green. This part of the insoluble material goes directly into the whisky well and dissolves in the strong alcohol present. Thus a part of the original volatile fatty material collects in the singling tank, and part finds its way into the whisky. The trade calls this material “verdigris” which is an unfortunate name since it has no connection with the verdigris of commerce.


The amount of this material is small in comparison to the volume of alcohol produced. Probably 250 grams per 30,000 liters of high wines would be a fair approximation, although no exact figures are available and would be very difficult to obtain.


UNSAPONIFIABLE MATTER. The ether extracts of the soap solutions upon evaporation yielded 1.4 grams of a viscous oil having somewhat the odor of corn.


The green solid when leached with hot alcohol was dissolved, leaving a brown solid. Upon filtering and cooling, the alcohol solution deposited green crystals; hence the palmitic acid is considered to be held as a cupric salt.


The higher fatty acids and their derivatives found in whisky verdigris without doubt originate mainly in the corn (3) which makes up from 60 to 89 per cent of the total grain used in making Bourbon whisky from which the sample was obtained. The corn oil alone does not offer an explanation of the presence of laurate and caprate esters, although Hilger (6) reported the free acids to be present in fusel oil. The occurrence of the various fatty acids and their derivatives in the beer is easily understood, but their presence in the distillate is more difficult to explain. Although it is known that the higher fatty acids are volatile in steam, or at least volatile in steam containing the vapors of more volatile acids, it must be remembered that this is not purely a steam distillation.


It is possible that the acids distill and cling to the copper condenser, and that partial salt formation (11) and esterification take place there. The majority of the esters are probably formed in the beer, and many other possibilities are obvious although none appears to explain satisfactorily the absence of stearic acid or its derivatives. Although this acid has been reported in fusel oil (6), the writers were unable to find any indication of its presence in whisky verdigris.


Whisky verdigris has a strong odor of green whisky and may be said to be yeasty: although none of the substances mentioned by Hochwalt and others (7) were found, their hydrogenation process may owe part of its effectiveness to the reduction of the unsaturated derivatives which otherwise become rancid.

These two photos come from rum distiller James Copeland christening a new still.

An accumulation of beautiful whiskey verdigris.

Insoluble flecks collected in a low wines receiver.

Whiskey verdigris can even end up as a precipitate in the tales fraction.

Insoluble flecks can be collected in cheese cloth suspected over the low wines receiver.

The last four photos were courtesy the wonderful Kings County Distillery which primarily produces a bourbon.

This last photo is from the Auchentoshan distillery in Scotland. Courtesy an astute reader with an eye that doesn’t miss much.

Feel free to write in and add to the photos. They can be attributed or submitted anonymously with the type of spirit distilled.

2016 Retrospective

Being December, it is time for the year end retrospective. Like usual, I felt like I didn’t accomplish much, but I did write about 20 posts with some containing distilled spirits’ most significant historic discoveries for the year (examining Arroyo) and others containing distilled spirits’ most progressive ideas (congeners derived from glycosides).

I have put a lot of beverage work on hold to become a design world darling and start the Houghton Street Foundry (IG: @houghtonstfoundry) which makes exquisite door hardware and offers architectural machining services. I have ghost written a few products for small distilleries with one being the hottest off premise specialty product in New England, though I actually think I designed it last calendar year. My beverage pace has slowed down, but I’m still holding significant technique and history secrets from the industry (to punish you all!).

The year started with Rum Comparatively: Understanding Anything Goes and explains how production compares to other spirits categories and why rum is the most progressive spirit with unique production templates that other categories do not use.

Aggressive collecting led me to Excise Anecdotes from Arrack Country which tells some of the most breath taking (and heart breaking) distilling stories ever recorded. It also ends with a beautiful discovery and meditation on terroir.

There is a ton of WTF? in Rum, Mitogenic Radiation & The Bio-photon. Brilliant Science writer, Adam Rogers, was cool enough to spend time weighing in so I had a lot of fun with the post. It does show that Rafael Arroyo was a far out thinker with an ear to the ground and yet again reinforces the idea of rum as the most progressive spirit. Nearly a century of science later not much is clarified.

This was particularly important to me because I’ve long been a champion of the rums of Cape Verde. In Cape Verde and Sugar Cane Juice Rum Categories I apply explanations from Arroyo to my favorite distilling tradition and explain the origins of their distinct aromas. There are so many supposed rum experts and they are still avoiding Cape Verde and the island of Madeira. Berry’s or Plantations rums, where you at? I’ll connect you to Cape Verde’s most brilliant distillery.

Here I describe my plan for discovering a new generation of champion rum yeasts: Team Pombe and the Yeast Olympiad. So far I haven’t been able to get it off the ground because of a lack of interest from the small distilleries in my circle (and the very expensive process). I will likely finance and execute the ideas by myself and I’m not afraid if it takes quick a few years. No one else seems to be too interested in this territory.

Rum, Osmotolerance and the Lash was so much more than a cute title and looks at forces that shape microbial communities, especially when trying to cultivate a dominant Pombe fermentation.

I had heard murmers of these ideas so long ago from Ed Hamilton so I decided to tackle them in Aroma Breakage and Rum Design. Arroyo as usual was on top of everything. Some new producers like Maggie Campbell of Privateer are known to be very much hip to this and weave the ideas in production.

Ageing, Accelerated Ageing, & Élevage ==> Lies, Damn Lies & Statistics This was my look at Arroyo’s progressive musing on the aging topic. I think this was before I read UC Davis great, Vernon Singleton’s, legendary paper which I probably should have given its own post (2017!)

Narrative of the 1975 Rum Symposium

Say it with me:
Rum is the most progressive spirits category.
Rum has the most researched spirits production.
There is nothing finer than rum as we make it.

There is so much good stuff in the symposium.

I had never done a spirits review before and of course I did it on my own terms. This post, Spirits Review: Mezan XO Jamaica Rum, also ends up with a challenge of drinking 10 ounces in one sitting to test a theory many are anecdotally validating. I also drop one of the most progressive ideas in all distilling and introduce a new congener category. Its not my fault if people cannot keep up.


Before I left to run a popup in Province Town this summer, I introduced For Sale: Large Bottle Bottler. This tool is particularly awesome but not for everyone and I don’t push it. Some bars are killing it with my bottlers and I am in some of the world’s top programs while other notable programs cannot assemble a team that can handle the tasks. A lot of a sales go to winemakers doing research projects for their own product development. I owe you all a new post on kegging to show you’ve all been doing it so so wrong.

In the frustration of the election and inspired by blog hero George Lakoff, I penned Public foundations for Private Spirits Companies. The post is a meditation on how private companies get built on a foundation of public research and how we are starting to forget that. A new generation of distilleries is popping up that often flounders with the technical aspects of product development because they do not seek out any of the amazing research that came before them. Most distillers are in disbelief the research exists when I introduce it to them. This rickety blog is the largest source of advanced educational material for the new American distilling industry which is approaching a billion dollars in revenue and quite a few hundred million in investment.


Here I introduce the Alaska Ice Crusher and describe a stunning restored version produced by a new friend. I’ve used Alaskas for a quite a few years and lately have been seeing them popping up in finer bars. They have become a Boston bar scene thing and collectively we own quite a few.

In A Few Papers For The Industrious I take a break from foundry work to read from papers that Rex sent in which I’d been hoping to come across for a few years now. Having gotten in the mood, I also shared up some delicious snippets from the archives of rum arcana.

Patrick Neilson Tells of Rum (Like No Other), 1871 This was easily my favorite piece of the entire years with its companion article J.S. Tells of Rum, Jamaica 1871. These papers kick off the fine rum era and are full of the choicest opinions on things like skimmings that many of us have heard of but don’t quite understand.

This piece was short and fun and simply shows that even as far back as 1885, which is a few life times out from the birth of the term, people were into tracking down etymologies: Etymology of the Word Rum by Darnell Davis (1885).

This is only for nerds and if you’re short on time and need to triage your reading, skip this, Occurance of Lime-Incrustations in Rum Stills (1903), and the next post, Scientific Control of a Rum Distillery by F. I. Scard.

As I collect papers, a genre of writings is emerging and this is an enjoyable example from a seldom described island. W. M. Miller Tells of Rum in Guyana for Timehri (1890)


We ended the year with the Return of the Champagne Bottle Manifold where I mastered single point threading on the manual engine lathe and started cutting the proprietary 19/32-18 threads myself to improve the design. My design over the years has evolved to be really spectacular, but they didn’t really catch on because programs didn’t want to pay for them and those that did had them frequently stolen. The most serious users ended up being Champagne sales reps.

Who knows what next year will bring. Sadly for the Bostonapothecary blog, my focus will be in the workshop. Ask questions or challenge me and I may sit down and post.


W. M. Miller Tells of Rum in Guyana for Timehri (1890)

In Guyana, rum had attracted yet another Victorian genius and that was W.M. Miller. His article for the amazing publication Timehri reinforces the idea that rum consistently attracted PhD level scientists to push it ever progressively forward.

This article is pretty cool and after reading so many of these I keep coming across little subtleties that show the evolution of ideas. Thinkers like Micko or Arroyo did not come out of nowhere, but rather came from a continuous line of thinkers at the forefront who were happy to share their ideas. Greatness in distillation is not about secrets, it is about execution.

In reports on estate’s work it may have a few lines devoted to it; but it is seldom that any genuine interest is taken in it, either in its manufacture or in its quality. The usual feeling is that the rum makes itself, and does not require any looking after. The molasses is diluted and the wash distilled; and if the results are low, the molasses is blamed; and if the rum is bad, the distiller gets a reminder.

Wine making itself is an adage & rhetoric of the terroir scene, but it is far from the truth. To bridge the gap, I try to differentiate between traditional processes and guided traditional processes.

But in these latter days there has been a brightening up of interest about rum. The Government meditate new legislation; and home buyers are becoming more fastidious owing to the quantities of continental root spirit, called “Rum,” that are thrown on the English market. This latter reason soon affects the manager of the estate, and for some time there is continuous rubbing of hands and sniffing, with more or less satisfaction—generally less.

Beautiful language and we see that old technique—rub a little spirit into the hands to open it it up, then sniff! The continental spirit is made from sugar beets and supposedly, though a lot of effort has been thrown at them, they just can’t make a product with aroma worthy of being called rum.

We have the misfortune to cater to a fancy of the most changeable type. So it is with rum. We have to suit an unknown personal taste, and, let us do our best, if we halve a sample, A. will laud it, while B. will probably call it “beastly stuff.” But the chances are that B. does not know what a good rum is, as the sniffing test is still fashionable; and we come back again to the desirability of a “polariscope,” wherein B’s taste is the optical part that indicates “beastly stuff.” In others words, if we had such ready chemical tests as could permanently record B’s taste in some fixed way, we should be able to avoid shocking B., and at the same time to please A.

A segmented market was on his mind. The polariscope idea is basically to turn a rum into a definite number. Even now with GC-MS we don’t know exactly what chemical compounds correlate with notions of quality. Personally, I love wandering in the realm of acquired tastes.

It is with the hope, therefore, that some universal method may be introduced, not only here but by the buyers also, so that every one’s particular liking may be recorded in figures, that I have come forward with the following contribution to the subject. The “everybody” in this case is probably a few individuals in two or three markets.

This became a bit of a quest for a lot of people, and I do enjoy the way Arroyo avoided it. We always need to remember that the occasion around a sensory experience adds rhetorical power and shapes taste while so does context and telling the story of a fine spirit. Taste, especially when cultivation becomes a hobby is especially malleable. We are no longer authentic hard laborers drinking the same product on end simply to quench our thirst and sooth our sores.

Another reason that should demand the more systematic analysis of rum is the desire to guard our product from being imitated by the Continental spirit. Unless analyses of the genuine spirit be well known and widely circulated, analysts would find some difficulty in distinguishing the genuine from the imitation.

These aspirations become very significant and the efforts also produced much better genuine rum.

The usual here is to allow the fermentation to proceed spontaneously, and if a return of 5 percent, to 6 percent, of 40 O.P. spirit be obtained from the wash set at 1o6o the result considered satisfactory.

Simply we note they were still practicing spontaneous fermentations, but we should think of these very differently than wine.

In practice, as before stated, it is usual to allow the fermentation to proceed spontaneously. The addition of sulphuric acid or ammonia sulphate does not in the least start the fermentation. They may, or may not, improve the wash and make it a more suitable medium for the development of the yeast, but unless yeast in some way gets added, the addition of any quantity of these bodies can be of no use in starting fermentation. During grinding operations little trouble is found in starting fermentation through the addition, one way or the other, of the highly fermentable washings and scums; but if distillation has to be conducted by itself, after a period of rest, the trouble in starting a good fermentation and the low results, will no doubt be remembered by any one who has had to deal with it. To find the reason of this we must consider what fermentation is.

Here is some juicy morsels. There was often trouble starting fermentations later in the season when skimmings were no longer available. It was not yet realized how to create a starter and how stages of yeast reproduction differed from stages of alcoholic fermentation.

But what is in the scums and skimming!? This is the cream if you remember. Are they particularly rich in the building blocks of yeast growth? and/or valueable aroma precursors like glycosides? Who knows and these fractions might not even exist anymore due to large advances in sugar processing. What is their official status?

Alcoholic fermentation is the change a saccharine solution undergoes when the yeast plant developes in it. Being a plant, yeast wants food very much the same as other plants, and unless the foods are there it will not develope. But every variety of plant has one special soil best suited to it ; and if it is our object to cultivate any particular plant, it is to our advantage to give it the food on which it flourishes best. Yeast requires carbohydrates such as glucose, mineral matter in the form of potassium phosphate with a little of the phosphates of lime and magnesia, and albumenoid bodies which must be in the soluble state. The reason why these foods must be in the soluble state, is that the yeast only feeds, as it were, through its skin.

Great metaphors. Arroyo had really great explanations of how fermentations get stuck.

In molasses, we have the carbohydrates and probably sufficient alkaline phosphates, but the soluble albumenoids are altogether wanting. It is owing to their absence that fermentation is not readily started in molasses. In cane juice, on the other hand, these albumenoids are in the best assimilable state, and hence the rapid fermentation that is so easily set up. We have here a very easy means then of establishing fermentation in molasses.

Here we go. I also suspect that the yeast count on the skins of canes or grapes or fruit, or anything not boiled like molasses is very significant and helps it burst into rapid fermentation.

A little “cush-cush” can be made at a moment’s notice, which, when once fermented, will serve to start the vat. The yeast when once started has the power to render soluble the insoluble albumenoids that exist in the molasses, so that the fermentation will then proceed of itself.

He drops the cush-cush! His explanation here may be spurious.

The advantage of establishing a vigorous and healthy fermentation cannot be too strongly recommended. It alone produces a pure alcohol. The languid insipid vat is productive of fusel oil, besides becoming an easy prey to the action of deleterious ferments.

Arroyo eventually takes the math of the starter to the nth degree and explains how to figure out how big exactly they should be and what is compromised when size changes.

The only means of escape then is to start such a vigorous fermentation that the predominance of the yeast will entirely obscure the harm done by the other ferments or kill them to a great extent; for in fermentation, as well as in everything else, it is only that which is adapted to the environment that flourishes.

Sage advice. There is the phenomenon of killer yeasts, but I’m not sure if that is what Miller is intuiting here.

As it is in the beginning of the fermentation that the lactic acid ferment is likely to get a hold, the necessity for quick starting of the alcoholic fermentation is obvious. Towards the end both the alcohol and the acid developed keeps it in check, but neither of these (the alcohol and acid) restrain much the action of the acetic acid ferment which begins to be very evident towards the end of the alcoholic fermentation. The appearance of a peculiar film on the surface of the wash indicates the presence of a species of Saccharomyces that is busy changing the spirit into acetic acid. It should be beaten down under the surface where it cannot obtain the oxygen necessary to destroy the spirit.

Interesting stuff in here. A lot of different things can grow in rum ferments and Miller probably knows a vinegar mother when he sees one (or smells one). I wouldn’t have thought it would be effective to punch it down below the surface. I’d have thought it would either float back up or be encouraged by whipping oxygen into the brew, but Miller seems like he achieves success. Was it common to witness all sorts of deleterious growths and deal with them as such? There are top fermenting saccharomyces yeasts, but this seems different. There are also weird mucusy growths that can turn a ferment into thick scum. When you’ve got them you’re on your way to a kombucha SCOBY.

This is not the Acetic Acid ferment proper. It develops throughout the whole wash and is quite a different organism. It flourishes best at the same temperature as yeast and is thus difficult to restrain,but as it only appears after the alcohol is formed, much damage by it may be avoided by distillation at once.

For me, this isn’t ringing a bell yet.

The butyric acid ferment feeds on the fatty matters present. It is to the acid that this ferment produces, in combination with the alcohol, that the flavour of rum is partly due. The distillation of the wash should be conducted as regularly as possible. Any rapid increase in the temperature forces over impurities that otherwise should be retained by the rectifier. The temperature at the exit of the rectifier should not exceed 18o deg, F.

The big reason pot still distillation needs to be slow and regular is that a more rapid boil challenges the subtle reflux contributed by the walls of the still. Reducing this subtle often over looked reflux drops the distillation proof and allows more congeners to come across in the hearts fraction. The spirit exiting should be kept cool so that it does not evaporate creating a loss and so as that it doesn’t dissolve the copper of the still. Inadequate condensing temp is a big problem for the bush rums of the world in places like Trinidad and Cape Verde.

I’ll skip Miller’s explanation of all the congener classes which is actually notably cool. He is wrong sometimes but shows how much they knew and how much they were willing to take a stab at back then. Brilliant.

Measure out 25 c.c. of the alcohol into a small glass flask, and drop in 15 c.c. strong sulphuric acid. Pure alcohol when treated in this way gives no colouration, but the presence of aldehyde gives the solution a brown colour, and the fusel oil a dark purple.

Arroyo practiced this test not to measure congeners by coloration like Miller but to chemically reveal rum oil. Other aromas are rendered neutral by reaction with the strong acid.

Tested in this way, the ” heads” of a still give very deep dark browns, which fall very quickly and give place to a pink with a trace of blue; which continues till about the time when the “low wines is cut,” when there is a sudden rise of colour, the dull purple predominating. The white rum itself can be tested in this way, and fair comparative results obtained.

Fascinating. I’ve been itching to do this test and was promised some surplus acid. I already hatching a plan for what can artfully be done with it.

The testing of rums which are already coloured, with sulphuric, of course cannot be done. It becomes first necessary to distill it from the colours. This should be done rapidly without the addition of any alkali, till all has passed over that can, without burning, the first-third and second-third being caught separate from the last. Halve each of the thirds, and mix them, this will represent the rum; and test the other portions separately. These separate portions will give further insight into the nature of the rum.

Very profound if you look at the ideas of Micko and Arroyo that come later. Let me quote it again:

These separate portions will give further insight into the nature of the rum.

This idea elaborated is everything.


Scientific Control of a Rum Distillery by F. I. Scard

This great (possibly 19-teens?) article from the International Sugar Journal by F. I. Scard immediately brings up some themes I’ve been talking about in distillation. For starters, Scard was a name who criticized the Veley’s in their debacle over the micro organism of faulty rum 91898). Remember the punchline?—the organism might simply have been decomposed raw meat! And the hint comes from a comment by IRS researcher extraordinaire, Peter Valaer in 1937. Can you not see this wicked web we’re weaving?

Any how, the idea I’m promoting is that just like fine wine did not exist without the lab, the same is true for spirits. The winners of the judgement of Paris were all lab guys and the same will be true for great distillers past and future, skipping the present.

In the case of a rum distillery the position is very different. It is not the sucrose alone which has to be accounted for in the course of manufacture, but all the formentable sugars, glucose, and invert sugar, as well as sucrose, which find their way to the distillery. The object of the operations of a distillery is not to separate and obtain these sugars as such, but as a product formed from them by biological means before its actual separation by distillation, a product in which the flavour is a vital point in its value. The microscope thus plays an important part in the control of a distillery.

Here we have language that sums up chemical and biological control and shows conscientiousness. The science goes on to get very heavy and shows that people of PhD level science education were involved in the production of fine rums. After much heavy duty science wanking Scard puts a time stamp on a known technique for making fine rums:

It sometimes happens that the wash is not sot up all at once, but that fermentation is allowed, purposely, to start before the set is completed, being gradually fed with “sweets” until the desired charge is obtained. In this case the constituents of the wash must be measured separately, and the sweets determined separately too.

Incremental feeding of washes was a technique further elaborated years later by Arroyo and may be unique to rum fermentations. He does later go on to criticize the technique possibly because it does not fit neatly into his idea of control.

As already mentioned, the microscope plays an important part in the control of the fermenting loft. The great enemy to fermentation is the putrefactive, bacillus and the wash requires to be constantly examined for the presence of these organism. A few are invariably present, but, if the condition of the wash is favourable to their development, the yeast plant is soon smothered, and there is nothing else to be done but to clean up the distillery in every detail. It is as well also to keep a microscopic eye on the yeast plant, to see if it is developing properly, and at the same time to look out for moulds or other organisms inimical to the yield of alcohol.

Oh, maybe we are not talking about fine rum here after all, but rather the commodity category? Fine products require a certain philosophy where control isn’t sought completely, but rather just enough control to frame windows for chaos. Arroyo later showed us the benefits of controlled putrefactive fermentation and aroma beneficial moulds. The rums of Hampden estates go on to tell a very singular story where they break all the rules and there is certainly no one going around “cleaning up the distillery in every detail.”

The number of gallons going to the still in the form of wash during the week is recorded, together with the amount of alcohol received from it. These should agree within 5 per cent, with a pot still and 1 per cent, with a continuous still. The lees, or spent wash, should also be examined for alcohol by distillation, daily in the case of a continuous still, and from every distillation with a pot still, to see if any alcohol is escaping in this way. 250 c.c. should be taken and 50 c.c. distilled off, the gravity of which is taken with a specific gravity bottle, and corrected for temperature, when any loss of alcohol will be at once discovered.

This test can be run with a profit motive, but if you put in the time, you’ll also learn about lost aroma. With a flipped motive, fine rums can benefit from many of the same protocols as commodity rums.

In order to ascertain the amount of spirit obscured, the following is a reliable and simple method, and preferable to the distillation method in the case of strong spirits like rum. The specific gravity of the coloured spirit is taken in a specific gravity bottle, or by Sikes’ tables, if the Sikes’ hydrometer is used. 100 c.c. are then taken and evaporated until all the spirit has been driven off, i.e., when the residue has reached a syrupy consistency. The residue is now dissolved in water, and made up accurately to 100 c.c. at the same temperature at which the gravity of the coloured spirit was obtained. The specific gravity is now taken. The decimal part of the gravity is then subtracted from the gravity of the coloured spirit, the remainder giving tho gravity of the spirit without the colour. From this gravity the quantity of alcohol present can be obtained by reference to tables.

Currently the TTB requires the distillation version of the test, but the version presented by Scard (and arrived at my myself independently years ago for studying liqueurs) is remarkably easy and with modern day instruments can be performed on remarkably small scales with amazing accuracy. Small, 5mL, volumes of historic rums could be sacrificed to get this data. There is huge criticism of obscuration in the rum world and yet no leading authority has been sophisticated enough to perform this test for themselves. From 5mL-10mL samples, and a collection of bottles, it would take very little from the rum community to look at the obscuration changes in many brands over recent history. If consumers feel obscuration is important to the fine rum category then here you go.

Faults in rum are found by the following test. A portion of the coloured rum taken from the cask before shipment is diluted with twice its volume of distilled water if it is strong rum of the Demorara description, or with an equal volume if of the weaker Jamaica kind. It is then placed in a small cylinder covered over with a glass plate, and allowed to stand for 24 hours. If at the end of this period there is no appearance of cloudiness the rum is free from “faults.” If a cloudiness appears it may be due to :—
(1) Resinous matter from the wood of the cask ;
(2) A precipitate from too-highly burnt colour ;
(8) The presence of low bodies of the fusel oil class which should have been kept back in the low wines.

Other reasons have popped up for faulty rum and I put up a great series of papers the other day.


Occurance of Lime-Incrustations in Rum Stills (1903)

This is a short fun one from the 1903 International Sugar Journal. Many of us think of old school rum washes as being quite dirty, but what toll did it take on equipment? And what does it tell us about Arroyo’s focus a few decades later?

By 1903 sulphuric acid was in wide spread use to acidity fermentations and that led to lots of salt deposits.

So all of the biggest concerns were from commodity rums produced on continuous column stills and not the fine rums produced on pot stills where they could simply discharge and then flush out.

This phenomenon where alcohol changes how the crystals form may be why I’ve had much better success creating sugar cubes in an alcohol/water solution than in water alone (a project from probably six years ago). Very interesting.

What he goes on to explain is that sugar and acidity in the wash increase the solubility of gypsum so that 1 part to 400 part drops considerably. Gypsum actually precipitates as the wash ferments because the sugar content decreases.

These ideas are before the era of the Alfa Laval continuous centrifuge.

It would be Arroyo’s focus to go on and solve a lot of these problems with new ideas in molasses pre-treatment which resulted in significant advances to commodity rum production. It is hard to say if Arroyo faced the exact same challenges. As sugar producers gained increased chemical control and gathered more data, they were able to produce higher quality molasses. A lot of what Arroyo removed from molasses was not exactly gypsum but gums and other materials that could impede fermentation besides clogging a continuous still.

Etymology of the Word Rum by Darnell Davis (1885)

A fun snippet from the files is this 1885 look at the etymology of the word rum. Judging by titles of his other works, the author, the honorable Darnell Davis, was quite the character, but so far I haven’t figured out if he was any kind of colonialist racist or not. Google has no full view of his essays, but I’ve yet to consult other resources (too busy at the foundry).

Davis’ work comes a whole 200 years after the birth of the word, rum, at a time that was pretty much the birth of modern rum with any stylistic identity (beginning of chemical and then later biological control).

Most enthusiasts today believe there are few works on the subject, but rum it turns out, has the most well documented history of any spirit category. This blog has become sort of a monument to and repository of that technical history.

Categorizing rum is all the rage, and lately in discussions, I’ve been promoting the top most categories of fine rum and commodity rum (which we will eventually sub categorize). This backs away from cliches like sipping and mixing as well as industrial and artisan. It is no revolution in rum categorization, but the words are semantically powerful and have been very valuable to understanding wine. Wine, we will repeatedly see, is where we should look when figuring out how to categorize and market rum.

My big point is that fine rums exist, and they are certainly out there on the market, but the category does not yet exist. We cannot have fine rums sorted from all the commodity junk until the complete history of rum comes out. We just went from thinking Jamaican rum was shrouded in mystery to finding out it has the most documented history of any spirit complete with time stamps, intimate anecdotes, and first names galore.

Fine wines tell a story, and that is largely their whole point, but we cannot read it unless we clearly know how they were produced. Things we don’t quite understand like the contribution of cane varieties cannot be pulled apart until the other variable are isolated by disclosure. We still have no wide acknowledgement of Schizosaccharomyces Pombe as a rum yeast. Giant holes exist in rum knowledge that would change any categorization system so I think a lot of people are getting ahead of themselves.

Fine rums cannot tell their story until we know more about them starting with their technical history and evolution. This has nothing to do with banishing caramel coloring or the arbitrary numbers attached to a solera system. Dwelling there will just set rum back. The future of fine rum literature will probably resemble Andrew Jefford’s writing on wine, but it is nowhere near there at the moment.

Darnell Davis’ 1885 etymology of rum is another step in telling the history of rum that will get us closer to the category of fine rum. Pulling these papers out is less about helping to produce better rum (like some of my efforts for new distillers) and more about helping to read rum. We need a continuous story from the birth of the word to the bottles we are currently enjoying.

Spirits get shaped by countless influences from the cultural to the philosophical to the scientific. Wars shape spirits and so do unique government programs like the various experiment stations or the infamous Rum Pilot Plant. The fine category begins with chemical and biological control to sculpt a spirit into an ideal and then the philosophical is free to take over.

Fine wine, we must remember, was born in the lab. The American winners of the Judgement of Paris were all lab technicians turned winemakers. This allowed them to follow the progressive process of incremental improvement for their wine. These producers, particularly Warren Winiarski, were deeply involved in the philosophical end of wine construction, but they also had the technical foundation to execute all their ideas.

Let’s quote Winiarski because it is wildly relevant:

That was also there. All of those things. We didn’t talk about the major ingredient, the accumulation of scientific information and things that people did at Davis. Maynard Amerine’s work with grapes and where they grow best –that bulletin of the Agriculture Experiment Station at the University of California that I used as a Bible, reading it in a devotional way. Every day you read a little bit of this, at night you read a little bit of that, getting intimately immersed in the contents. You read another chapter and tried to figure out what these must analyses could mean and what their significance was. The existence of such a rich body of knowledge was certainly another major ingredient. And I think the other thing was the people, among whom I count myself, whose taste and aspirations were formed elsewhere and who brought in the ability to actually accomplish the coming together of these several elements.

Maynard Amerine and the culture of that UC Davis era have always been a guide for the work at the Bostonapothecary. A Winiarski or a Grgich of the rum world will not come along until we assemble and digest all the literature. Also, notice that Winiarski et al. were studying texts meant for commodity wine production. These fine wine makers literally sat in (old school non degree sat in) the back of the class to learn anything that might help them produce fine wines. What are the differences between fine and commodity? Philosophy, scale, and compromise.

A big problem the new distilling movement has is a shoddy notion of philosophical ideals and absolutely zero chemical and biological control. With few exceptions, they have all pretty much only gotten as far as: “look mom, I made rum”. And of course it is not rum, which is a concept that pops up in the literature time and again, best reinforced by Arroyo. Not all things made from sugar cane products are rum and if they’re not rum, they are in the commodity category. The commodity category has things that aren’t fit to be called rum as well as things fit to be called rum, but not fit to be called fine. Right now we are seeing some of the most expensive commodity distillates ever produced hitting the market from the new distilling scene.

Skimmings communicate in a far greater degree than molasses the characteristic stamp to rum. A spirit made of pure molasses and water would scarcely be rum; and instances are familiar of molasses having been removed from one place and distilled at another, which, with different skimmings, have produced an entirely different rum. -J.S., 1871

Ideas evolved a bit and rum, according to Arroyo, starts with a rum yeast, and what is special about that yeast is that it takes advantage of precursors in the substrate to produce extraordinary congeners, of low frequency of occurrence, and of universal harmonic value, all the while limiting congeners like fusel oil which overshadow when in excess. Yet we’ve only learned all that recently by rediscovering literature that had been lost for decades.

Just like the chemical and biological aspects of rum production have a history, so too does the philosophical and that heritage goes back much further than anyone had recently thought. Just the other day, a paper turns up from 1871 with an author (J.S. also quoted above) describing the idea of forcing versus intercepting flavour. Though it is proto-philosophy, the concept sit parallel to the idea of wines of effort versus wines of terroir.

Only with recently revealed technical history could we read more of the story of the fine rums of Cape Verde because much of their unique character has to do with their sugar cane juice not being centrifuged and defecated like the rhums of Martinique.

Don’t forget that many of the fine rums of the last ten years from independent bottlers such as Plantation were not very conscientious nor produced with much enlightened philosophy. They were found art, accidentally over aged, and accidentally ending up extraordinary after missing their modest targets. Their architects weren’t part of contemporary culinary with their own twitter accounts, but were often government employees and at the most generous, many could be called outsider artists (brilliant and conscientious, but within a tiny bubble). The faceless nature and the way so many producers imploded is a big part of the intrigue for the sleeping relics they left behind. But on distilling day for the 1986 Barbados rum bottled by Plantation, if you said fine or asked about forcing or intercepting flavour, the Barbados boys would say: ‘the fuck you talk’n about?’ It was distilled like a brick house, but with commodity ambitions as the basis for some anonymous blend somewhere.

Anyhow, read Darnell Davis and marvel at his tracing the etymologies of rum and his tales of digging through the libraries of Europe to do it.

J.S. Tells of Rum, Jamaica 1871

Alongside Patrick Neilson in the 1871 edition of The Sugar Cane was this account by an author signed J.S. I’m supposed to be putting down my investigations on rum to focus on the Houghton Street Foundry, but I could not resist.

The J.S. account is of a slightly different perspective, so it may be helpful to comb through it and see how it lines up. J.S. seems relatively less focused on rum production and more involved with cane cultivation and sugar production. Half of J.S.’s article is about cultivation issues before going into rum production, but I’ll skip that.

Leaving the sugar to drain, let us return to the millhouse to collect materials for the distillery. Mill-bed trash, sour, or rat-spoiled cane, suckers, &c., are all collected and ground for the purpose of making rum. Then from the boiling-house is taken the trash and lees from syphons, and skimmings from the coppers. All these meet and mingle in a large receiver, or mixing vat, which is continually ebbing and refilling, and kept fermenting. From this a certain quantity is put in the bottom of each vat or cistern to be set up, generally about 250 gallons to a vat of 1000, which with 475 gallons Dunder, 200 gallons of water, and 75 gallons molasses, will make up a vat of liquor standing thus by Long’s saccharometer (which shows degrees of specific gravity above water, and about 7½ to 1 of Baumé’s scale):

For starters, these guys were smart and he goes on to crush math with fractions like a savant. Anyone in Jamaican operating at the birth of rum’s stylistic identity was well educated.

J.S. is also describing a system very much like Patrick Neilson’s where the trash cistern is being used as a sort of yeast/bacteria generator and that footing is used to setup the entire wash. He writes sort of clinically and does not sing the praises of the individual raw materials like Neilson.

The above should take about six days to ferment, and is an average specimen of the wash set and distilled here; but on each side of this average there are considerable variations, some setting at so low a degree of gravity that fermentation is over in two days—others so high that is may take two weeks. This can be done without materially interfering with the percentage of sweets added, or return of spirit produced, the dunder being the medium effecting this, which may be kept at any standard of gravity from 20 to 60.

Maybe we should reference Rum, Osmotolerance, and the Lash. Without changing the percentage of sweets, a.k.a. fermentable sugars, other variables can extend or shorten the duration of fermentation. Arroyo really pushes an understanding of this to the max.

Such differences in the mode of treating wash does not fail in producing corresponding variations in the quality of rums—that from the waterish and quickly fermented liquor being of a harsh and bare alcoholic odour; while the other, even new from the still, will smell mild and full-bodied. It is nevertheless asserted that the former turns out the more drinkable article by age, as is said to be the case of whisky of a similar stamp distilled from raw grain. Notwithstanding the superior character of Jamaica rum in general, there arises baffling dissimilarities in the flavour and value of rums made even on neighboring estates—the price realised for one being sometimes nearly double that of the other. That such differences would give rise to various speculations as to their cause, as well as endeavours at competition, is but natural to infer. Such endeavours have not been few, nor unattended in single instances with fair results, but the theories alighted on by experimentalists are varied and incongruous. The means adopted are principally confined to the treatment of the wash in fermentation. Pursuing the course indicated by the fact that better rum being producing by slow fermentation, the direction has been followed to the utmost limit consistent with a reasonable sacrifice of quantity and quality. Such sluggish fermentations are often induced as to present  not only unmistakable signs of a highly acetous, but an apparently morbose process, which instead of dissipating—as might be inferred of a rapid process—tend to fix, develop, or dissolve (as chemical investigation might determine) the aromatic principle (or substance containing such) constituting the valued flavour. Were the result attending this rather hazardous experiment always a success, we might be contented to abide by the conclusion that this aroma is entirely the effect of a certain process of fermentation; but as such fails to be the fact, the more natural supposition seems to be that it is a peculiarity incidental to certain soils, extracted principally by the albuminous matters of the cane juice and sent in the skimmings to the still-house.

#morboseprocess Here we she admission of “experimentalists”, probably of the like of Neilson, who are developing the early Jamaican rum process. At the very end J.S. also notes the importance of skimmings.

In commendation of this it may be stated that flavour is always strongest in the bottom part of the wash in the fermenting vat, when the albumen and yeast, &c., have subsided after fermentation. It is to be remarked, however, that rums of the most natural and most valued flavours are made in the most ordinary way, and without any effort of forcing, which fact directs and strengthens the belief that flavours may be intercepted, but not directly forced, by fermentation. I believe the water used in setting to have more connection in imparting flavours than is generally allowed. It is beyond dispute that the superiority of Scotch Glenlivat and Irish Poteen whiskies is owing to the soft, mellow, sweetish waters derived from surrounding peat bogs, and using in mashing and brewing. These whiskies are to all others what Jamaica is with rum.

A very subtle admission happens here when J.S. grapples with intercepting versus forcing flavours. My reading is that there is an admission of peculiar character other than esters which is rum oil. Esters are forced by the #morboseprocess while rum oil is thought to be intercepted and dissolved from products like the skimmings. Rum oil has been bred out of our rums but when you find it, you’ll know it. Esters can be faked in contrived ways, as I’ve stated so many times before, but rum oil is nearly divine. Rum oil is produced during fermentation through the hydrolysis of glycosides (a discovery first reported on this blog but pretty much stolen from the latest Cognac literature) and many variables such as a long fermentation, and even a resting stage, increase the potential to split the glycosides. Please see: Mezan XO challenge.

Skimmings communicate in a far greater degree than molasses the characteristic stamp to rum. A spirit made of pure molasses and water would scarcely be rum; and instances are familiar of molasses having been removed from one place and distilled at another, which, with different skimmings, have produced an entirely different rum.

This is a powerful statement that parallels much of what was said by Neilson and draws into question the greatness of New England rums. The current naive generation of new New England rums scarcely have any rum character and this I believe is what J.S. is talking about. However, decades later, Harris Eastman Sawyer would enter the fray in New England, and judging by his few writings as well as his sales to the tobacco industry, Eastman was able to make a rum purely from molasses that had that peculiar character.

Among other efforts to impart a flavour may be noticed that of adding certain odorous ingredients to the wash previous to distillation, or lucious fruits during fermentation. Of distillation little need be said. The apparatuses used are the common still for wash and generally retorts for the high and low wines. Low still heads are approved of as admitting more free passage for essential oils, but with these caution must be used in firing, so as not to force over bad oils which ought to remain in the lees, and at the same time prevent foul running. The running should be conducted slowly so as to cause the spirit to arrive perfectly condensed and cool. Flavour is always strongest in the first half of the spirit from the still, and it is sometimes the practice to put this up separately, and ship it under a different brand from the other.

For starters, we are catching up with some of Jamaican rum’s infamous  myths, but without much specificity. We also see that J.S. was conscious of the shape of the still head influencing the flavor of the distillate (low still heads). Foul running likely implies an overly rapid boiling creating foam that spills over through the condensor and into the distillate. Isolating for sale the first half of the distillate is a primitive form of super fractionation I’ve talked abut in the past where distillates are chopped up into more than the traditional fractions and reassembled as specific products. The big incentive of it here is because the taxes are so atrociously high and the market is fairly efficient. German buyers are happy to bid up the price based on how far they can stretch the concentrate, and the tax will be the same no mater what, so there is a big incentive to remove anything neutral from the rum. The reason this doesn’t really work in producing a truly great product is because the most valued congener, rum oil, is not in the first half, but rather a product that appears in the second half alongside fusel oil (hence benefit of colder fermentations).

That rum has not only been the staple and principle support of the many ill paying estates during bad years, but has acted indirectly as a barrier to the introduction of improvement in sugar manufacture, even on highly remunerative properties, there can be little reason to doubt. Proprietors when asked to adopt such and such an improvement, or send out certain new machinery, at once become jealous of the quality and proportion of their rum, and answer “no,” making such excuses as that they expect greater improvements to be arrived in course. The invention of the concrete process—the latest stride in advance—was not in the direction of Jamaica, unless for exceptional estates producing rum, so poor in quality as to be of the remotest consideration.

The concrete process is where cane juice is vacuum concentrated into bricks. No molasses is separated. Jamaica was very slow to adopt new sugar producing efficiencies because it, at the time, was far more successful in rum producing than anyone else. Producers were putting high value on byproducts like quality molasses or skimmings that were less rum beneficial in more sugar efficient processes.

Not only is ordinary rum netting £15 per puncheon, sometimes a more profitable article than sugar, but high classed brand at £18 to £25 per puncheon∗ in such cases make sugar quite a secondary consideration, and often attempt the turning of such an undue proportion of materials down to the still house as to seriously affect the value of the rum itself. So long as this state of matters continues, there is little likelihood of an sudden changes in our boiling houses here, yet it is to be hoped, as well as expected (especially should the recent favourable years continue, with returning confidence and capital to the island), that as the old taches and syphons become “burned out,” more advanced methods of manufacture will be adopted, having for their object the turning of cane juice to the best possible account, in the direction of its more legitimate end—namely sugar.


Trelawny, Jamaica,
23rd January, 1871.

J.S. appears to think that rum is morally inferior to sugar production and morality somewhat has an influence on the economics of can cultivation. This moral sentiment had profound influence on other islands and was the reason rum production never took off on Hawaii. No doubt there are quite a few other examples.

All in all, J.S. seems quite aware of all the ins and outs of rum production with an ear to the ground, but he is no experimentalist like Patrick Neilson. A deeply flawed moral conviction keeps his interest always with sugar over rum and that is just sad.

Patrick Neilson Tells of Rum (Like No Other), 1871

I’m supposed to be working on a new photo shoot for the Houghton Street Foundry, but I couldn’t resist sharing up this pearl of rum history.

A note from my archives which I had shared up the other day had a wonderful quote by Scotsman in Jamaica, Patrick Neilson. It was hinted that he wrote a great paper on rum in one of the very first editions of The Sugar Cane.

I will easily say that it is one of the most significant papers on the topic of early Jamaica rum. It is a ten page origin story that draws from his European experience, the opinions of the German buyers, anecdotes galore, and it just plain fills in a lot of gaps. Neilson’s pursuits are also aroma-centric and I think he is setting a precedent in the literature (1871).

Neilson tells of the mythic rum canes (which so far exist in reference nowhere else but this blog), early ripening canes having more aroma, and Bourbon cane producing his favorite rum. The German buyers paid the most for the first five batches of the season and we find out why. There are admissions of “lucious fruits”, the likely arrival at a pombe fermentation, small estates doing it better. Read it for yourself.

Neilson supports a big point that this blog has been driving for years, which is that distillation itself is no big deal and he glosses over it. Fermentation and the raw materials are everything. My Distiller’s Workbook has always aimed at giving a thorough understanding of still operation so that involvement can be deepened in the other stages. The still operator can be an intern while the fermentation chemist is everything.

Its 1871 and Patrick Neilson is expounding the virtues of slow fermentations and cool temperatures.

[…] quite the opposite to the system usually carried on, namely, the hurrying in of all material, keeping the vats boiling like a pot, fermentation over in three days, closed doors and a heated apartment, consigning all the refuse and bottoms to a dirty cistern, where all, or at least a considerable portion is in a manner lost.”

I would have thought by all I’ve read that the legendary long fermentations started much later but this is 1871.

In order to show the great difference that exists between quick and slow fermentation we have only to look at the method pursued in some parts of Germany for the production of what is known as Bavarian beer, which is the product of a very slow and protracted fermentation, combined with a low temperature, for a full description thereof I would refer to Liebig’s works—a few extracts here however will serve my purpose so far,

This is exciting to me because I want to know where the ideas came from. Now Neilson quotes Liebig:

“the wort after having been treated with hops in the usual manner is thrown into wide flat vessels, in which a large surface of the liquid is exposed to the air, the fermentation is allowed to proceed while the temperature of the chamber in which the vessels are placed is never allowed to rise above 60°. The fermentation lasts from three to six weeks, and the carbonic acid evolved during its continuance is not in large bubbles which burst upon the surface of the liquid but in small bubbles like those which escape from an acidulous mineral water, a great deal of yeast is deposited on the bottom of the vessel in the form of a viscous sediment; this precipitated yeast does not excite ordinary fermentation again, and when the yeast is used again several times in succession the temperature may be increased much higher.”

I highlight the whole quote because Patrick single it out (by now he is Patrick to me). This check list is on his mind and you see such differentiation of fermentation phenomena on the minds of other Jamaican rum chroniclers that came much later. Vat size and shape would become important and would be a factor others were in tune to as they pursued fermentation with symbiotic cultures.

The beer so obtained is entirely different and far superior to many other sorts; and if this superiority is got simply from a slower fermentation  then I hold that like results may be obtained in rum making.

Jamaican rum styles were not evolving out of the success of neglect or anything like that, they were being directly inspired by beer!

What in fact first drew my attention to seeking out a flavour in rum was the running I first got from what is known here as the dirty cistern, a receptacle for all the refuse, bottoms, &c. of the other vats; I was astonished to find at the can pit mouth, as the run came over, an exquisite flavour. I considered and said, why not make all the other vats, dirty cisterns, or at least to come extent, and I proceeded accordingly, with very happy results.

This is the very first experiment with cane trash and it has a time stamp and a first name. After this the ferments get a little more complex and feature more cane byproducts and ratios of cane byproducts as seen in the Experiment Station works.

I may state that the said dirty cistern besides being a receptacle for all refuse, is allowed to go on fermenting away, sometimes dead, sometimes alive, for three or four weeks; in fact, a sort of putrefaction goes on, and an acidity is produced which frees the aroma, hence a fine flavour when full.

This is some fine organoleptic investigation. What I think he is noticing is that fermentations are going on that produce all manner of fatty acids. Alkaline lime marl is also being added, but not intentionally as will come later in history. At this point its just excess from cane boiling. The lime alters pH, restarting fermentation when it runs away and becomes too acidic. The lime also has an affinity for shorter chain less noble fatty acids and it frees longer chain acids that were previously bound as salts. This is more pronounced as the cistern gets full of liquid and that is what Patrick is noticing. In the not too distant future they will know all the specifics.

Following up my ideas, I then proceeded to turn half of the vats, gradually increasing up to two-thirds, into slow fermentation, and commenced by adding material in small quantities to each vat. The vats were about six feet deep, holding about 2000 gallons. I only put in liquor to cover about two feet at the commencement and added from day to day as I saw them dying off, keeping them always gently excited till they were filled up. I kept them moving this way for two weeks, sometimes less, sometimes even more.

I see this as wildly important and I’ve been collecting these anecdotes about the very beginnings of the seasons where practices may differ from later on. Every detail influences the microbial community. Patrick may have been starting a fission yeast Pombe ferment as opposed to a conventional budding yeast ferment. Whatever trash he started with may have dropped the pH low even that an alt yeast took hold.

As these vats began to work I soon found a rich fruity odour pervading the house, and I then knew I had the right thing, which was confirmed at the can pit mouth.

On resetting up these vats I did not as customary, pitch the bottoms into the dirty cistern, but set up again on them, continuing to so for three or four successive occasions when the liquor began to get muddy and I had to throw them out.

What Patrick is describing here is a back slopping technique often used in Cachaca ferments. A microbial community will soon evolve to an equilibrium. The yeast though can get tired and they may require conditions better suited for reproduction.

I found at about the third setting up, a round from which I obtained the finest flavour, after that the vat began to get too heavy and sluggish besides acid. I then threw the whole away, dunder included, and drew from the other third, that is, I kept one-third of the vats working on the old system, for the sole purpose of obtaining a fresh and sweet dunder.

Without chemical control, they have yet to be working on continuous system and instead are on everything third batch you start again.

By setting up on these bottoms I extracted all their virtues, not so by a dirty cistern, it is far too clogged up, and there is not half enough liquor in it for the solubility of the precipitations, there is a loss there also, as the dunder has to be thrown away at every running of a dirty cistern.

This shows the more primitive system Patrick was getting away from. They knew there was alcohol in the byproduct and they periodically ran it through the still.

By thus working I changed the character of the fermentation very soon, only small bubbles working on the surface quite gently, something like an acidulous mineral spring.

Noticing something different, he may have found our hero Pombe.

When I wrote my first paper on the subject it gave rise to some comment—why could I only make two-thirds of my rum crop good and not the whole?

I highlight this because we may find that article.

Besides that, I then quietly withdrew all my low wine stills. I was the first to do this, but it has now become a common practice on many estates. I would however suggest that these low wine stills be redistilled—it would take away the low winey flavour.

This is a little hard to interpret and I think it means that they started to find, now that they were producing more aroma, more virtue in fractions further along the run.

In addition to what has been said, there are many minor details requisite for procuring flavour, none more so than getting plenty of Rum Cane liquor, that is the half rotten or rat eaten cane, unsuitable for sugar and generally sent to the still house, not at all for flavour, but from economical motives, however the bookkeeper often gets flavour thereby quite unwittingly. The rum canes have gone through a process themselves of a slow fermentation, lying in the field and yard, hence their efficacy.

This to me is among the most exciting parts of the paper because it discusses a tradition that may have been completely erased. If a microbial community needs to be created from scratch, this may be the place to look. It would likely be the subject of an awesome PhD paper. This also parallels whole cluster fermentation in wine grapes and is known to produce a distinct character with specific chemical markers.

I have known some estates making rum one year worth £25 in England, and the next only getting £17. I could trace it to the want of rum cane; when rum cane is not to be had, sweet cane liquor is as good only subjected to proper treatment.

Cane liquor likely being fresh sugar cane juice which brings its microbial community because it was not sterilized in the boilers like molasses. The experiment station documents decades later make use of lots of fresh sugar cane juice and if I remember correctly fail to acknowledge the rum cane. I suspect hat as more trained scientists entered the fray they absolutely could not rap their heads around rat eaten cane.

Another indispensable article is skimmings; a distiller cannot get too much of these. I have seen some estates giving away the half of them to the working mules, they were very probably throwing away £5 per puncheon; very few mules now enjoy that beverage, the value being better understood.

We all know of skimmings but we have not seen such an endorsement nor such an anecdote!

The skimmings are the fat or cream of the liquor, and it is for want of that commodity that our large distillers in the United Kingdom can only distill guid Scotch whiskey out of molasses, in place of rum. Skimmings are a powerful agent in fermentation, and vats set up with molasses alone will not yield nearly as much as when mixed with a proportion of skimmings. Skimmings have a very acid reaction.

Hell of an opening metaphor and “guid” is a little Robert Burns-esque slang sort of like guid enough for a drunk. Euphonically it explains itself (I consulted David Ferry who had a lot of fun doing the voices). What I have not found is a chemical look at skimmings. How do they boost aroma? Do they hold the mythic glycosides? New England rums, we must remember, had no skimmings.

I believe that temperature has something to do with making a good spirit,—”heat yer maut slow and ye will get the sweeter liquor” is an old Scotch saying, perhaps applicable here; it may be owing to this that our October brewing of ales at home are always the best.

Oh yeah? Tell us more…

I often thought that in the beginning of the crop here, that is after the first round of vats, that the best rum was made, owing to the temperature—January being very cool. I have also heard German rum buyers here say that they have engaged whole crops of rum on the faith of the first five puncheons submitted to them, but towards the end of the crop they were miserably disappointed.

These anecdotes are treasure.

Canes also, scarcely ripe, will produce much more for the stillhouse, and bye the way, flavour also; even cane tops in a dry season are a very good thing for rum—just as good as rum cane, sometimes better.

Oh really Patrick? [bats eyelashes]

What also affects cane juice, but in flavour of the stillhouse, is the distance sometimes that the grinding apparatus is from the coppers, especially where there are windmills, the liquor has often to travel 200 yard in an open gutter. That the manner of boiling  cane juice does affect after products is shown by the fact which I heard stated on good authority, that where on an estate usually producing a good rum, they were compelled, owing to an accident in their machinery, to send their canes to be ground in a neighboring estate, the rum turned out perfectly different.

Patrick and I may or may not be half way through a Mezan XO challenge. Write drunk, edit sober.

What sort of cane is most favourable for good rum it would be difficult to say, but I certainly prefer the Bourbon.


Leaving the fermentation house, we come to the last process in rum making, namely, the distillation of the fermented wash or liquor, this is so simple that no description is necessary. The still in use here are mostly those having one or two retorts, which produce rum at one distillation, there are a few estates yet using the old single still, which involves three distinct distillation and great extra expense for fuel and attendance. It would be difficult to say which still produces the best rum. One would imagine that with the retorts great opposition is offered to the essential oils, or flavour coming over, and yet some of our best rum are obtained by retorts.


I have seen some bookkeepers using the spent lees of the retorts again, saying they get better returns; there never was a greater fallacy, and of all things I would eschew this, the low winey poison is just what I would seek to avoid. It is amusing to hear the different opinions about loading the retorts, the fact being that as long as the induction pipe is covered it is all the same, the alcohol will come over, it may be either in rum or low wines. To save trouble it is best to keep strong spirit in the retorts, and when kept up a better spirit is got. Consign weak rum to the low wine cistern.

When Patrick says spent lees of the retorts he is describing a fraction that doesn’t usually have a name. He says lees but there are no yeast present. This fraction is the non-volatized part of a fraction already distilled. It is mainly water, fusel oils, and less volatile fatty acids. When I’ve discussed the loops of fraction recycling in the past, this fraction is a point where things exit the loop and are not recycled.

I will close my paper with a few general remarks on the subject. It has been observed that few very large estates make fine rum—always the smaller ones. I account for this by the bookkeeper being obliged to keep pace with the large crop, and in consequence, hurry on all his materials. Molasses, for instance, should not be used till they are a week or two old, they oxydize as it were, and certainly change their character. Perhaps it is from other causes that our “we still whiskey” at home is famed.

Another important matter that will affect rum is the quality of the water used. I believe that the name of some our more celebrated brewers and distillers in England depends upon this.

Here we have Patrick christening the category of fine rum (as opposed to commodity rum) in 1871. I try and reinforce these as the too highest level categories of spirits. Mixing and sipping are cliches that should die as well as industrial and artisanal. A commodity producer can produce a fine product even on industrial equipment.

Fine and commodity also better capture quality for purpose and justify the existence of other styles. I’ve discussed in the past that some rum producers have realities we fail to recognize. Short fermentations often exist because of pressure to move substrate along. The molasses is stacking up. These producers are not cheating anyone and they price their products appropriately. We undervalue commodity producers and as urban American hipsters fail to recognize that the laborers of the world need an affordable drunk.

A Few Papers For The Industrious

I’ve taken a break from the blog to start a door hardware company, but wonderful papers keep rolling in and I’ve been hoarding quite a few notables that in the right hands can move the industry. I’m not ready to share them yet, but I will share a few others.

Rex recently brought up a paper that I have written about a few times but apparently never shared. DW Clutton has written some of the most interesting things about gin over the years and supposedly has a new one on the market I’m itching to try (can anyone arrange for Clutton to be interviewed on the Bostonapothecary?).

Rex was also kind enough to share up a great series of curiosities that has been on my list so long I forgot about it. In the early 1960’s, L.A. Warwicker wrote a three part (I, II, III) series about instability in potable spirits. This was the era before stainless steel and apparently before filter pads become more inert. This was also when Arroyo‘s teachings of how spirits can be broken by dilution were lost.

Do new American distilleries have instability issues? I’m just not in tuned any more. I do remember seeing lots of strange condensation in the exposed neck of filled bottles and hearing that it could be remedied by setting up a bottle washer that rinsed new bottles with the product to be filled.

I did also experiment with using common sand as a filtration media to remove excess terpenes from gin with a lot of success.

In the spring, I collected a lot of notes on rum. I’ll share the briefest ones, a favorite being a note on the moral superiority of rum (a must read).

This note from 1921 provides a time stamp on the idea that Trawlany was still churning out full flavored rum despite the serious industry slump.

Associated with Guadalupe, Rhums de fantasie according to this 1921 note were apparently fabricated rhum-like products which drove down the price of the genuine article. I did recently have a nip of one that was bottled in the 1970’s.

If we go way way back, we can invoke Patrick Neilson of Trelawny who describes the “dirty cistern”.

“what in fact first drew my attention to seeking out a flavour in rum was the running I first got from what is known here was the ‘dirty cistern,’ a receptacle for all the refuse, bottoms, etc., of the other vats; I was astonished for find at the can pit mouth as the rum came over, an exquisite flavour . . .”

Oh yes, and scoring big bostonapothecary points, there is a mention of the rum cane I’ve been talking up. “that is rotten or half eaten cane, which had been allowed to undergo a slow fermentation while lying in the field and yard.”

So, there is a first name, and a time stamp, and a reference to even more literature written by Patrick Neilson. Have at it.

The lost rums and early investigators really make a mockery of the new distilling scene in sophistication of inquiry. This note with a citation for Keyser’s original paper even looked at vat size and shape for optimizing aroma production from schizosaccharomyces pombe. I have more from Keyser elsewhere I should share up.

H.H. Cousins, who invented the high ester process, was optimistic that a generation of British WWI soldiers exposed to the comforts of Jamaican rum during the war would return to it as civilians. He was also hip to rotating bananas and sugar cane in the fields of St. Catherine.

At the same time that British soldiers were drinking a type of Jamaican rum, the German market for German rum was collapsing. In this note, distillers producing German rums actually change up their production to common clean. Its easy to gloss over this, but it implies that they knew how to shift gears and were not so worried about losing the ability to resume production of full flavored rum (coffin full of muck, mold on the walls). It also reinforces the idea that there were very different economies to producing each style.

[… the causation of the complaint. As an instance of this we may mention that in the rum from the several distilleries which are under the control of one of us, faultiness, which of late has been found on mark only, has been distinctly traced to the use, in this particular case, of packages made from comparatively new and uncured staves.

We may remind your readers that in certain wine-growing districts the wood intended for use in packages is tested by portions of it being soaked in brandy for some weeks, and samples causing in the spirits used, upon dilution with water, the turbidity which in rums is termed faultiness, are rejected.
We have the honour to be, Sir,
Your obedient servants,
J.B. Harrison,
Frederic J. Scard.
Georgetown, British Guiana,
May 9th, 1900.

Meanwhile in Paraguay, at Empresa Azucarera, description of a lost rum of unique prodcution…

A superior quality of rum is distilled in Paraguay, being made from uncrushed cane. Small amounts of this spirit have been shipped to Germany and, it is said, obtained good prices.

Are we missing a few details? Is this carbonic maceration with whole canes fermenting within liquid juice, or something else? If anyone still did anything like this it would be a chachaca here and there at the beginning of the season.

Spirits Review: Mezan XO Jamaica Rum

The Mezan XO Jamaica rum is likely the greatest deal in all of spirits at the moment, yet it has been slow to catch on. Even in this unprecedented era of spirits education buyers seem slow to discover anything. The product is a very smart blend likely assembled by E & A Sheer, who has unparalleled access to blending stocks. The product forgoes traditional coloring and subtle sugaring giving it a very sleek modern truth seeking quality.

Despite a righteous flavor and probable noble E & A Sheer heritage, the branding comes across as a vodka startup like veneer that may irk some. Don’t fall into that trap, the gates to MGP whiskey may be wide open, but access to the lost rums of the world is elusive and I recommend taking it any way you can get it.

This rum from Mezan has that je ne sais quoi, and that is appreciable quantities of rum oil, the most noble (if not divine!) of all the congeners. The new generation of spirits connoisseurs is slowly digesting the concept of esters, but the king congener class is the fairly high boiling point terpenes that are the product of glycoside hydrolysis (these are different from gin botanical terpenes). This is absolutely at the forefront of distillation research, being led by Cognac and also finds itself at the forefront of theoretical oenology where researchers are pointing to the same congener class as a significant layer of the terroir phenomenon.

You can fake esters, but you cannot fake rum oil. If you target esters in your production you will produce some rum oil, but if you target rum oil you maximize your potential and you get all the esters you want at the same time. This is easier said that done and was the dogged pursuit of the 1940’s rum researcher, Rafael Arroyo (it is pretty much what his 1945 book is all about). Production ends up requiring a virtuosic attention to detail or wild amount of divine chance. It is hard to say how the producers behind Mezan XO do it.

Two distilleries can start with the same substrate and thus the same amount of glycosides yet end up with wildly different amounts of rum oil. This aroma can be seen as silent or bound aroma that needs to be unlocked with care. Glycosides are typically split via enzymes produced by yeast. Alt, non-sacharomyces yeasts produce far more enzymes than typical sacharomyces (think budding bakers or brewers yeasts). This is where our hero from other posts, Schizosacharomyces Pombe, comes in (as well as a few others).

Catalysts, like acidity, also act to increase rum oil production as well as that expensive ingredient of time. Longer fermentations (and resting periods) yield more opportunity for glycoside hydrolysis, but at the risk of aroma-detrimental bacterial infections. Risk is worth money and that is why we should prize this congener class. Authenticity is also worth money, and unlike esters, this congener class is something that cannot be faked. There is no easy road to rum oil.

We are building up to the Mezan XO challenge, but first we need to go a little bit further.

Many spirits of great repute have lost this congener class as their production has been scaled upwards because no one really knew where it originated. The main loss comes from migration to low risk pure culture fermentations adopted by many formerly traditional distilleries because typical sacharomyces yeast produce less of the enzymes needed to split glycosides. Besides spirits, this has profound implications for wine. Pure culture fermentations forgo a lot of this aroma because they result in a much narrower microbial community. For spirits, tequila may have been the most negatively affected by yeast changes as production scaled up.

Devastating changes to a spirit often happen when a distillery changes physical buildings as result of increasing production because so much of the microbial community is held in the architecture. Hampden estates, with some production areas covered in aroma-beneficial molds, is the perfect nth degree case study while others like the cult beer producer Cantillion are also notable.

So little basic science has been done on architecture embedded microbial communities that we don’t even know how they start or get balanced forming a SCOBY (I have a collection of anecdotes!). Aroma-beneficial molds are often over looked in Jamaican rum production in favor of aroma-beneficial ester producing bacteria, but they likely have their origins in the long forgotten “rum canes”. When Jamaican rum wash bills used percentages of fresh sugar cane juice, it likely came from Rum Canes which were canes infected with molds. These could be analogous to the noble rot in wine grapes, but definitely different in the finer points. They might not even exist anymore having been eradicated by modern cultivation methods and pesticides and thus only available through the physical buildings we take for granted.

We’re getting closer to the Mezan XO challenge, but first we have to look at the end of rum science history in the 1990’s and how and why Cognac took over. Rum science seems to end in the 1990’s with a call to explore alt yeasts but never directly pointing the finger at aroma from glycosides as the most significant source of rum quality. Cognac picks up where rum leaves off for some really interesting reasons. This means that if we want to advance rum further we have to look to Cognac and some of the ideas at the forefront of oenology research.

Bon vivants will note that there is a lot of overlapping character between the finest rums and the finest Cognacs. Many rums historically were designed to mimic Cognac. Grapes used for Cognac production are also high in glycosides. Cognac production also has a few other properties overlapping with rum we could go into, but I’ll spare you.

Cognac oil as a congener class, just like rum oil, has been recognized for over a hundred years, but the big driving force behind why the torch was passed to Cognac is because they have their back up against a wall. Everyone else focuses on expansion instead of quality improvement, but Cognac is a small region and their product has been legendary for centuries. They have cultivated near all viable area. They cannot expand, they can only improve so that is where they spend their energies and do it so well.

We can only hope the new American distilleries end up similarly with their back up against a wall. Right now they are all trying to expand rapidly, forgoing quality. If new American distilleries balloon from 600 to 3000, the focus will likely go from expansion to quality improvement as a way of staying competitive.

Cognac researchers are also notably in tune with their heritage and they bring us from an era of traditional practices to guided traditional practices. Chaotic diversified microbial communities are the hallmark of traditional practices and science is starting to recognize the importance of minority community member’s role of producing the rarest most extraordinary aroma. Tradition alone, in this context, is associated with ignorance and ideology best exemplified in the sloppy natural wines flooding the market. While guided tradition recognizes the science behind the chaos, does not seek to master it so much as frame careful windows around it to reign in the risk. The resultant products are consistently extraordinary (In wine, I would single out Randall Grahm immediately, but so many deserve cognition).

Before the Mezan XO challenge I’d quickly like to note that certain Armagnacs are very high in aroma from glycosides and they can be very hard to tell apart from Jamaica rums. Certain tequilas are notably high, but fewer than there used to be. Older rums from cult producers had it and lost it. Use your nose and keep track (there are also a few amazing chemical tests taught by Arroyo*). If we highlight exemplary producers they will become stronger guided traditionalists and be mindful as they scale up to global demands.

(*The most basic test is to take a 2 oz. sample and add sulfuric acid which will destroy all the esters and aldehydes subtracting their aroma. If strong residual aroma remains, it can be attributed to the rum oil congener class. This sample is now undrinkable!)

Rum oil, Cognac oil, and aroma derived from glycosides may have pharmacological effects, that is what the challenge is about. If you drink spirits high in these congeners you may feel significantly less dehydrated by the ethanol. Your buzz may seem to hang broadly in a really lovely way. It is a different drunk with lots of anecdotal evidence to support it. Search your recollections, have you ever experienced something like it? Is rum oil the pattern behind mysterious lack of hangover after significant consumption? Are wines of terroir more gentle?

Most all congener classes have been widely studied and ruled out as specifically contributing to hangovers in broad populations. Rum oil has not been studied because of near no awareness and that it is appreciable in less than 1% of all spirits. It is the product of very specific microbial communities just like so many drugs, there is no scientific reason to immediately dismiss its unique potential power.

Remember, I am the guy perceptive enough to have identified all of the olfactory illusions in the wild categorized by Richard Stevenson. When wallowing through subjectivity, my track record of acuteness rivals a neurologist.

I encourage any devoted bon vivant to take the Mezan XO challenge and consume appreciable amounts of the spirit (safely) and note the effects. Do this especially if you are aging and your tolerance for alcohol is changing negatively hangover wise. Who can afford to crush eight ounces of Martel Cordon Bleu, but anyone can afford Mezan XO. Sacrifice your body for speculative science. Design controlled drinking experiments. Supply of truly fine spirits will not come without demand and here I am unraveling the chemical pattern. No hangover research has been focused enough to look at a mythic congener class that is barely acknowledged and not widely available on the market. Maybe we can inspire researchers to pursue it. What comes before the science? This.

Take the Mezan XO challenge and/or search your recollections then please leave a comment!