Manufacture of Rum, Jamaica, 1889.

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There is a lot to say about this unique first person account of late 19th rum production in Jamaica. How does this compare to the works that came decades before this? The Great Agricola, W.F. Whitehouse? Leonard Wray himself in 1848? J.S. in 1871? Patrick Neilson?

The essay begins with a general overview of bio transformations as the author understands them which is quite interesting and Pasteur is eventually evoked. The author is plainly wrong frequently and our job is to understand why but also how some practices effect production in oblique ways not intended.

What yeast is the author using? Fission yeast or budding yeast? There is no clean cut answer from the description even though the author mentions Saccharomyces Cerevisae when invoking Pasteur.

What pH is the author shooting for? pH was not yet understood and my goodness is there lime everywhere!

Essay on the manufacture of Rum
by Samuel Stricker

Hillside Vere.
[and later associated with Amity Hall]


Vegetable substances undergo decomposition into their ultimate particles or atoms as soon as the vital function ceases and such decay is classified according to its action on the constituents of the subject, in the presence of light, heat, air and water, or in the absence of either of these forces and elements.

Fermentation, one of the class, is sub-divided, according to inversion and germification, into the vinous, mucous, lactous, butyrous, etc., each phase being determined by its specific acid and germ.

[Notice a broad definition of fermentation is presented similar to what I was asked to write in the Oxford Companion to Spirits and Cocktails.]

All substances in which saccharine matter forms the chief portion require the presence of an acid, a mineral salt, and a nitrogenous albuminoid, in solution, attended by the influences of heat, light and air. In the first place the sugar must be inverted if it be of crystallizable sort, into glucose by acidulation and the most expeditious mode is certainly the best, for if the inversion be slowly effected the fermentation is extended over a greater period of time, and the alcohol through the action of air acidulates, and is changed into acetic acid. This acid the product of acetous ferment, if used to effect inversion, prepares the yeast for reception of the germ common to that fermentation.

[Inversion of the sugars becomes a constant concern of the author and I’m not sure if it has any merit. Is it because Jamaican molasses at the time still retained a significant amount of sucrose or just a concept they speculate is worth being paranoid about even though there are no tools to observe it? This first part is sort of tedious before the section on Jamaica rum begins.]

The phenomena of inversion must not be confounded with that of germification; they are phases distinctly separate in their functions, although to some extent interdependent. For instance the inversion of cane sugar into dextrose and levulose, and the formation of prussic acid by amagdylln, and various other changes are distinguished mainly by increase of weight due to contraction of volume without evolution of gases, characteristic of inversion, and on the other hand, decrease of weight due to expansion attended by evolution of gases characteristic of germification.

Each acid has its specific action, thus carbonic acid produced by the vinous fermentation determines the germification if it be the medium of inversion, and this fact is borne out by practice, for dunder rich in this acid is used in Jamaica for the purpose.

[It sounds like the author suggests that CO2 entrained in dunder is strong enough to invert sugars and that is part of the justification for using it.]

Temperature influences the life and propagation of the specific germ in a remarkable degree. If the saccharine liquid is provided with albuminoids, etc., and be inverted by heat (which rearranges the atoms by molecular action allowing the minerals suspended to produce inversion) and the temperature be maintained at or near the boiling point, all germs are destroyed and cannot exercise their functions under this condition, but if the temperature be lowered within the range of existence they immediately propagate in it, thus showing the necessity of allowing free access of air in which these germs reside. If a solution of sugar be inverted by acids, or minerals and be placed in a suitable receptacle and sealed in the absence of air, and then heated to destroy the germs that may have got into the solution, fermentation cannot take place, but if air be present germification takes place, and fermentation ensues. Pasteur proves that if the air be filtered through a medium fine enough to arrest these germs, the fermentation will not commence until free access is allowed.

[I was surprised to see the author guided by Pasteur when it is commonly thought that Jamaican production flouts Pasteur’s teachings.]

All fermentive germs are of Fungoid growth, save that of the butyrous, which is excited by a peculiar infusoria. That of the vinous is termed Saccharomyces cerevisiae—of the lactous Penicellium Glaucum and of the acetous Mycoderma Aceti. The mucous and acetous possess the highest range of temperature, the next in the scale is the lactous while the vinous is lowest. Those of high range once determined exist in the same solution with the lower and proceed in the fermentation common to them, but the initial temperature according to time and duration, and alkalinity, neutrality or acidity of the solution determines which germ shall prevail. Heat as applied to germification simply destroys germ growth or presents a liquid having a temperature suitable to the germ. It can not determine the phase directly, which is the function of the acid and germ combined.

[The unfusoria language comes from a particular paper by Pasteur published in 1861. The author mentions Saccharomyces cerevisiae, but I am not convinced he has a microscope to make the observations. Percival Greg will become the first to observe fission yeasts in Jamaica ferments a few years after this is published. Another common mycoderma is Mycoderma Vini which grows in the presence of oxygen and produces very little. It seems to be the most common thing you see growing on dunder and may help create an anaerobic environment.]

If cane juice be brought to the boiling point and allowed to subside a precipitation of albuminoids take place, but a white nonazotised substance requires the presence of an alkali before it is eliminated, it converts cane sugar into a substance between starch and gluten, forms quickly and abundantly in syrups, rendering them viscid. The mucous fermentation is chiefly determined by this substance when it is in excess in the plant—the product of which is manite and gum. This fermentation commonly seen in skimmings is true fermentation; carbonic anhydride is evolved, although neither acid nor alcohol is produced. It is checked by acids and determined by nascent hydrogen. The manite and gum obtained by the process precipitates and forms a kind of granulation called Everlasting Seed in Jamaica in which the germs multiply with great rapidity.

[Carbonic anhydride is simply CO2. This is the first reference to Everlasting Seed I have ever seen. What best parallels the description is this passage taken from Kervegant. Granulation may be a medical reference to certain types of tissue that can grow instead of skin; granuloma.

Leuconostoc mesenteroides is a streptococcus, in the form of spherical grains surrounded by a glairy sheath (dextran). In the young state, it affects the appearance of a string of small grains surrounded by gelatin, then long refractory puddings, which curl irregularly while keeping in their axis the rosaries of grains that gave birth to them. Different tubes, curling up on themselves, form mucous bodies, constantly enlarging, and whose contoured surface resembles that of the brain, then masses more and more voluminous. The fermentation terminated, the grains soften and the rosaries break up.

I bet the author has seen things that have given him distiller’s PTSD. I have seen little neglected experiments with cane juice produce growths that were horrifying. I cannot imagine it on the larger scale.]

The butyrous succeeds the lactous fermentation, but if lactic acid be neutralized as it forms, the latter will proceed but a change takes place when the germ food is altered by the addition of caseine, decaying gluten or a suitable animal membrane.

[The author is describing in general these ferments and references dairy, sour dough, and sausage making. This isn’t rum production yet, but we see they were broadly knowledgeable that time.]

This is a putrefactive fermentation produced by grafting animal and vegetable substances undergoing decomposition.

It must be observed that the liquid in which the lactous fermentation prevails, requires to be slightly alkaline in contradistinction to the vinous which does best in a neutral solution, and the acetous and butyrous which proceeds best in an acid liquid.

[We do know that common lactic acid bacteria can grow in acidic environments and drop the pH in rum towards 4.0. They can also produce acetic acid as well as lactic.]

The mineral acids act quickly in producing fermentation but some of the mineral bases are deleterious to germ growth. Scard and others of Demerara use sulphuric acid with great effect. Inversion is quickly effected by this agent and the vinous fermentation speedily sets in, and nitrogen is supplied in the form of ammonia to aid the germ growth. The rum manufactured by this process is equal to that of any other place, when the same material is used, and the method superior, seeing that nearly the whole of the spirit indicated is recovered. Demerara Rums are manufactured with much less albuminoids than those of this Island, and for that reason have not the same amount of ethers, and although other conditions enter as factors, such as a more equal temperature, yet deficiency of this substance is the main cause.

[We find the author is acutely aware of the Demerara process and even the scientist that led it:

SCARD (F.I.). — Scientific control of a rum distillery. Int. Sug. J. 498-502, 1916.

This is 25 years later from Scard, but beats the same drum. In the paragraph, we also see an admission that albuminoid scum is directly understood to be tied to esters, but what is the background science? If distilleries use mostly imported molasses and no longer have skimmings, how are the effect of skimmings synthesized today? This awareness also appears here 15 years before Charles Allen reinforces the idea in 1905 in the Experiment Station writings.]

Mineral salts are requisite, especially phosphates and sulphates. Pasteur found that pure yeast deficient of mineral salts, did not produce fermentation when incorporated with a sugar solution, until the addition of the salts of ammonia and a soluble phosphate.

In the foregoing chapter, I have collated the chemistry of the process of fermentation, as far as it affects rum manufacture and now interpret the system we pursue in this island.

Our method is to collect the skimmings into a receiver, mix a portion with a proportion of dunder, molasses, and a quantity of water, allowing the mixture to contain about 12% of sweets. It is then allowed to ferment and when ebullition ceases, and the temperature has fallen, the rum is distilled off. In the first place the skimmings are obtained in this manner. The juice of the canes is expressed by a Rolling Mill and is pumped or gravitated into a receptacle provided with heating surfaces termed a clarifier. Heat is applied to the juice in this vessel until the boiling point or 180°F is obtained, when the albuminoids suspended coagulates and precipitate, but owing to the presence of acids in the Juice a portion is still suspended, until a chemical agent is exhibited which neutralises the acids and allows the heat to have free action; a further coagulation takes place on the copperwall, and by these means the juice is presumably freed of albuminoids and supposed to contain sugar, and water in which it is suspended. The water is driven off by heat, and the residue consisting of molasses and sugar allowed to crystallize in suitable receptacles. Massecuite resulting from this process consists of cane sugar, invert sugar, mineral salt of the cane juice, along with yeast that has escaped defecation and water of suspension. Owing to melassigenic action of the salts a portion of the cane sugar escapes crystallization, and is suspended in the molasses; the latter having been drained off from the crystals of sugar, is sent to the distillery to be manufactured into Rum.

[Kervegant can teach us a little more about albuminous materials:

Nitrogen is found in cane juice in the form of proteinaceous matter (proteins proper and nucleoproteins), coagulable by heat; proteoses (albumoses and peptones), products of hydrolytic degradation of the preceding materials, not coagulable by heat; amino acids and amides; and finally mineral materials (nitrates and ammoniacal salts). Proteins and proteoses are in colloidal solution, the others in true solution.

Kervegant keeps going and is worth a read. Keep in mind this is albumin native to the cane itself. Albumin from spent yeast is a different story.]

Directly as the Juice is expressed from the canes and come in contact with the air, inversion and germification commences, for it passes from the mill bed by means of a gutter, at a temperature between 80° or 90°F presenting a liquid having affinity for carbonic acid and oxygen of the air, and possessing invert sugar before expression; this change takes place quickly.

Germification is however eliminated by the heat to which the juice is subjected at subsequent stages.

The juice having been decanted the skimmings consisting of the coagulum and the portion of juice in which it is suspended, along with the scum from the copperwall is gravitated by means of gutters or piping into the skimmings pit of the distillery.

Surfaces over or through which, such a liquid has passed, presents to the air a thin stratum of liquid, and fermentation sets in and impregnates the liquors that pass over them subsequently. If the means of conveyance be kept clean and neutral, the vinous fermentation is sure to set in, but if neglected, a thick viscid scum forms on the sides in which acetous or lactous germs prevail. Our labour and skill is directed to obtain rum from the material, which is the product of the vinous fermentation, but if the liquid in question is impregnated with deleterous ferments in this manner by these germs, whose products are acetic and lactic acids, some portion of the liquid will be converted into these undesirable acids.

[Here we see the desire to have fermentation by yeast in the skimmings possibly implying the skimmings were a type of starter. Ambiguous language on this issue will follow and it is never made obvious.]

This deleterious action also takes place in the skimmings pit and receivers, and in fact throughout the whole of the distillery where surfaces of the description coming in contact with material, are exposed to atmospheric action. The surfaces are not to be kept acid or alkaline but neutral, so as to facilitate the vinous germ growth.

[Keep in mind, the pH concept was not yet invented. We can only bet they were aiming for the range of pH 5.8 to 6.2 but pH is logarithmic so at that point you are very close to neutrality in terms of titration. Without the pH concept, there is so much opportunity for their process to get out of control.]

The skimmings having arrived at the distillery is allowed to cool down, and the requisite quantity pumped into the distillery mixing cistern to be set up with the wash. There are two opinions which seem to clash, but which in reality do not.

Some distillers maintain that better results are obtained if the skimmings be drawn into the mixing cistern warm, while others maintain that it should be used at the normal temperature.

If the cistern is foul the longer the liquid is in contact with its surfaces the greater the amount of deleterious impregnation, but considering that the body of liquid to which the skimmings is to be added will either rise or fall in temperature according to the amount of heat abstracted or added, it should be drawn in at the temperature of the mixing cistern, so as not to alter the temperature of the wash in that receptacle. If the skimming cistern is in good order and kept so by the addition of molasses, the temperature should be nearly the same as in the mixing cistern, and if colder, one of two conditions is indicated, it has not commenced fermenting or is undergoing deleterious fermentation, perhaps the lactous owing to the presence of lime precipitated from the clarifiers, or the yeast has decomposed the sugar and determined the acetous germs, probably it may be the mucous, which once seen is never forgotten. In the first stages, it gives the skimmings a ropy, viscous appearance, and if it be not checked by sulphuric acid or other agents the manite and gum precipitates, and forms Everlasting Seed. The gas evolved is principally hydrogen which will act upon all the sugar and albuminoids in which it is brought in contact determining those germs throughout the distillery. It is very rapid and does not seem to be eliminated by heat, or by any other agent, save sulphuric acid, potash and salt in the first stages. It is better to dispense with the liquid and use sulphuric acid to wash the surfaces of the receptacles, when the precipitate shows signs of increasing. For these reasons, adding the skimmings at lowest temperature is practiced before fermentation has set in, but this can only be effected in small manufactories, where supply is equal to demand or less, none of the material being kept on hand. Hot skimmings should never be used, for the same reasons applying to hot dunder.

[A lot goes on in this paragraph and we even see a PTSD flareup at mention of Everlasting Seed which is likely due to too alkaline conditions. A hint is that an amount of molasses is added to the skimmings cistern but the reason why is mysterious. We also see the author threatening to use sulfuric acid to clean the vats and prevent the spread of undesirable bacteria throughout the distillery. Something we never thought we’d hear a Jamaican distiller say! Finally, we see a recommendation of adding skimmings before fermentation has set in. It is possibly that adding molasses to skimmings aims to prevent Leuconostoc bacteria which is more prevalent in cane than molasses as far as I can tell. It should be noted that Leonard Wray did not believe in the mixing cistern so they had been around for decades but not universally used.]


Dunder or wash from which alcohol and ethers have been distilled is used to produce inversion and promote germ growth. According to Pasteur, fermented wash contains ethylic alcohol, carbonic and succinic acids, glycerine, cellulose, essential oils of the cane, yeast, and sugar that has escaped fermentation. By distillation the ethylic alcohol is obtained as rum, and portions of the acids pass over in the weaker distillates. Dunder then consists of the residue plus caramel which has been formed by the charring effect of the fire, on the unfermented sugar, and which gives the rich chocolate colored hue to the liquid. This complex substance possesses all the requisites for inverting crystallizable sugar and aiding germification by reason of the yeast and carbonic acid it contains, and also exercises beneficial action by checking decomposition of the yeast by means of the empyreumatic oils and other substances contained in it. It should not contain more than 0.002% of carbonic acid, and should be distilled long after the spirit has passed away. 35% of the wash put in the still is about the least quantity that should be taken off in rum, wines and lees. If the distiller takes care to take off this amount, and keep the receptacles clean, deleterious fermentation will be absent from his distillery, for it is in the dunder that the acids and decomposed yeast ultimately come, and if they be not distilled off and modified increase and determine the mycoderma aceti or penicillium glaucum germ throughout the liquids. Many modes of neutralising the effect of these acids are pursued, but the best method is to add lime to neutrality to the wash in the still and distill off a quantity of lees. The lime will precipitate in the dunder pit along with the decomposed yeast leaving the liquid free of acid and germ food. Some distillers supply albuminoids in vegetable form and an alkali such as lime or ash to the wash, but although this method is the best for obtaining attenuation it is inferior to the plan recommended.

[This idea of distilling of 35% of the liquid volume is kind of wild and the reasoning seems more aimed at the dunder than capturing high value steam volatile congeners! (Remember Le Cognac?) The author really tries to connect running the still for so long to preparing the dunder in some way that prevents problems when it is reused. The exact logic of when lime is added is ambiguous. The only logic I can stretch my mind to is that lime is being added after the distilling run and everything is being boiled a little longer thus “and distill off a quantity of lees”. Lees here being essentially steam volatile tails. I would love to hear anyone else’s interpretation. My brain is just running wild, free of germ food? Were they really able to ferment at fairly high pH without incurring LAB infections? The idea of vegetable albumin is soon resolved.]

The common practice is to supply the albumen of Bastard Cedar or ochroe mixed with ashes. The alkali precipitates the yeast and the albumen takes the place of the precipitated yeast, thus enabling the vinous fermentation to take place in the same liquor. Although the yeast has been precipitated and acid neutralised in this manner, yet sugar has been used up for other purposes. Some of the sugar has been converted into saccharin, an unfermentable substance (not to be confounded with the saccharin produced from coal tar) by the action of the alkalion levulose, some has escaped fermentation, and the yield of rum will be less than if the vinous fermentation had been determined at the start, for the precipitated yeast containing the deleterious germ will be dissolved and come again into action by the solvent power of the acids subsequently formed and the acetous fermentation sets in before the desired point of attenuation is reached. For these reasons the neutralisation should take place in the still, and the precipitate of the dunder separated from the clear portion of the liquid thus eliminating the decomposed yeast.

[In the early 19th century Bastard Cedar was proposed by Louis Duboc (associated with Monsieur Dorian) as an idea to clarify cane juice. Okra is particularly high in albumin and it has been wondered by others as early as 1863 if it could be used to clarify sugar. Leonard Wray proposes the use of Bastard Cedar in his text, but never acknowledges actually putting it to use.

This makes you wonder if either ideas have parallels with Jackfruit use? I had previously chalked up Jackfruit contribution to being high in pantothenic acid which as a nutrient is sometimes used to build malo-lactic bacteria starters for the wine industry. Again they are racking off clear dunder to remove any liability from nutrients. I’m not so sure how the intentions would pan out in practice. Do they get a dunder that has very little free amino nitrogen?]

The use of lime is injurious to a certain extent, for it precipitates all the yeast and oils in the dunder and forms saccharin, but the sugar contained in it will be recovered, also the unprecipitable matter and these will pass again into vinous fermentation on the addition of the yeast of fresh skimmings and seeing that the greater portion of the yeast eliminated from the dunder consists of matter modified by deleterious germification the injurious action of the lime is more confined to the formation of saccharin and other unfermentable products than any other action.

[Here, things get confusing because the author alternates to talking about dead and live yeasts. Then we see more evidence of skimmings as source of fresh yeast.]

Live dunder is caused chiefly by excess of sugar in solution. This condition is caused by the yeast being precipitated before the sugar has been resolved into alcohol and carbonic anhydride and on cooling the ferment is brought into action again by contact with air and the fermentation is renewed, but if the froth resulting from this process be white, acetous germs is the cause and neutralisation should immediately be effected although the fermentation proceeds.

[More obsession with cleanliness and use of heavily limed dunder.]

Hot dunder should never be drawn down into the mixing cistern, it causes the acetous fermentation, for it forms the bulk of the wash and being at a high temperature coagulates the yeast in the first instance, and by reason of its temperature, causes the acetous germs to propagate rapidly under favorable circumstances, the vinous being excluded by heat of the solution.

If a copper pump be used to elevate the dunder a good plan is to observe the effect of the acids on the portion immersed in the liquid, if it keeps bright excess of acid is indicated and more lees should be taken off, and neutralisation effected. The barrel of the pump should be coated, with oxide.

[This a little tricky to unpack because more lees could involve distilling more to remove volatile acidity or liming the dunder closer to neutrality and decanting of lees as in spent yeast.]


Molasses is the residue of the sugar which owing to melassigenic action has not been crystallized. It consists of cane sugar, levulose, dextrose, yeast, mineral salts and a small quantity of acid. If it be brought in contact with water, a slow protracted fermentation sets in, and owing to its concentrated condition the circulation of the atoms take place slowly, thus presenting a highly carbonized dense solution to the air. Alcohol is formed firstly by the vinous ferment, but the surface on which this action has taken place, is largely extended in relation to mass matter and circulation, and for these reasons, the alcohol is converted into acetic acid, as soon as it forms, and thereafter directly determines the acetous fermentation. In the same manner acetic acid is formed by the air acting on the surface of the liquid in the vats and cisterns. Some distillers cover the tops of these receptacles to exclude the air as much as possible after the wash has started, for the germification having been effected, air is no longer necessary, but the temperature must be kept down by artificial means or the alcohol distills (by reason of the generation of heat) through the vent along with the carbonic anhydride. The mineral salts necessary for fermentation are found chiefly in this product, exercising melassigenic action during the concentration of the massecuite, and is drained off in the molasses, from the sugar crystals.

[Something we see here is that open top fermentation was not always the rule in Jamaica during the 19th century.]


The proportion of water exercises considerable influence on the fermentation by the oxygen and hydrogen it contains and tends to hasten the process when it is present in excess. This action seems to be due chiefly to the oxygen. Dunder on the contrary, by influence of the empyreumatic compounds suspended in it slows down the process, and advantage is taken of these facts to control attenuation. Frequently the wash presents a healthy appearance, and yet it is too high in temperature, and rapid in attenuation indicating the use of more dunder and less water; hydrogen is found in the gas evolved in excessive quantity and if the conditions are not changed in time, it determines the lactous or mucous fermentation.

[It is wild to ponder what this all adds up to. Can they really be fairly high pH in all likelihood (a concept they are not aware of) and use dunder to prevent lactic acid bacteria? The author also doesn’t tell you anything of their objectives relating to spirit quality. Does too high a temperature correlate to excess fusel oil in their mind?


The mixing cistern is the receptacle in which the wash is mixed, and is the centre at which the whole mass of liquors is inverted and the fermentation determined. This cistern is never emptied, except for cleaning purposes, and when a portion of wash is pumped up into the vats to allow space for fresh settings. It is to this cistern that a competent distiller devotes his attention. After some experience he can tell by the bubbles, colour of the froth, and various other signs the state of the fermentation, and from what source the wash has derived its bad qualities if such exist. For light rums the density of the solution should not exceed 1.070 or about 25° Arnaboldi, which is the specific gravity suited to 84° temperature, the mean heat of our atmosphere. This has been ascertained by direct experiment.

[For starters, it seems like this is a largish-vat that is only partially drawn down with the hopes that appreciable yeast are always present. I have seen descriptions of the same system still appearing decades later. What is called Spontaneous fermentation may emerge from these vats that are basically never completely drawn down and always have a degree of active fermentation. I’m not aware of any new rum distillers trying to practice spontaneous fermentation and using such a system.]

The rate of attenuation and temperature extending over the same period of time, should be as uniform as possible save when the fermentation has nearly ceased. If the fermentation is rapid and the temperature high excess of yeast is indicated, if the amount of dilution has not exceeded the rate mentioned previously, and it is safe practice, to add more saccharine matter to take advantage of the condition. Excess of yeast generally throws up a frothy head composed of medium size bubbles of dirty appearance at the rims, but transparent at their centres, breaking in patches at intervals. If the bubbles be perfectly transparent and large with ordinary attenuation, say 5° Arnaboldi for 24 hours the right proportion exists. Under the condition where the yeast appears to be in excess, if molasses be added to the wash and the head is still covered by the same dirty edged bubbles, even if the attentuations has decreased the cistern requires cleaning, for the acetous germs have multiplied in excess of the vinous. The wash pumped out should be neutralised at the still as soon as fermentation has terminated so as to counteract its effect in the dunder at the same time the skimmings receiver and pit should be cleaned out too, and both the wash and the remainder of the skimmings treated with bastard cedar or any other source of vegetable albumen and ashes. The colour of the froth is also indicative of the kind of ferment. If it be white the acetous is present. Healthy wash should be of a rich cream colour. It may happen that molasses is in excess, and owing to deficiency of yeast, the fermentation goes on slowly such symptom is characterised by the absence of bubbles and if acidity be present, a thick viscid cream, white in colour, covers the head of the wash in which bubbles break singly and almost simultaneously. Hot dunder is indicated when the bubbles are uniform, and form in hillocks of a rich brown colour when the wash is healthy, and white when it is acid; excess of this liquid throws up an oily head, in which the bubbles do not burst readily.

[Wow, what a charged paragraph! Have you ever heard of someone practicing spontaneous fermentation and complaining of too much yeast? When heavy spontaneous fermentations are described as ending in four days or some short duration it is either because attenuation is accepted as being very low (ferments less than 5% ABV) or they are using a mixing cistern with a long residence time and a low draw down. Does a distillery like Hampden use one mixing cistern or do they have several? It is very exciting to think about. We can start to take every distillery’s Instagram fermentation photos and start to diagnose them like a backseat driver. MORE DUNDER! IT’S NOT A RICH ENOUGH CREAM! #ALLCAPS I do feel like I have observed the last description of an oily head where the bubbles do not burst readily. I have seen very little acetous ferments, possibly due to temperature, but have observed lactic acid bacteria that can produce acetic acid sticking a ferment.]

If these characteristics have escaped observation at the mixing cistern, the wash, if possible, should be drawn down from the vats into it, and the proportion of dunder, molasses and yeast required, be incorporated, and the acidity, if any, neutralised in the manner pointed out.

[I am betting that if you have to clean the mixing cistern within the season, you restart it with a vat that is still doing the correct things. What we never hear about his how clean the fermenting vats are kept.]

The mucous fermentation is fully described in the paragraph on skimmings and the same remarks apply here.

The fermentation having terminated the wash is gravitated into the still and the rum distilled off.

[I am reminded of a description of a filthy distillery in St. Kitts-Nevis described by J. Steele in 1903:

I visited a distillery belonging to this gentleman not far from Basseterre, and never saw anywhere such a filthy and broken down looking place. Filthy everywhere. Filthy outside the fermenting room. Filthy inside. In the yard it was difficult to get over the stagnant and pestilential matter that one met with everywhere. The spirit store is dark and filthy, oozy and dripping from above, owing to the overflow from the fermenting vessels, slimy below, and stinking. So much was this the case that the distiller had, contrary to Ordinance, to fill the casks of rum outside the door on a spot elevated somewhat above the prevailing filth. Surely the Government should have power to shut up such a noisome place until it is put into a sanitary condition. How any Government official can take stock of spirits in such a hideous place I am a loss to know.

What is relevant is that the mixing cistern is on the first floor and that is pumped to a second floor (which can leak and ooze) and then that is fed by gravity back down to the stills on the first floor. Despite how we romanticize 19th century Jamaican distilleries, isn’t this description (of St. Kitts) very contrary to what we see described by Stricker in Jamaica at the Hillside estate in Vere?]

I have not entered into the subject of flavored rum for many reasons, and my remarks are entirely confined to the manufacture of the ordinary rum obtained from the vinous fermentation.


Alcohol boils at 173°F but owing to the density of the wash a much higher degree is necessary. The heat however should be allowed to fall as soon as the wines in the retort have arrived at the boiling point. Water vapourises at 212° and in some descriptions of apparatus, advantage is taken of this fact, such as the continuous still. This method has not been found of as much utility as the ordinary description in use here, which is the single still and double or single retort, chiefly for this reason. In other colonies, the spent wash or dunder is not used to promote fermentation, and acids being present in it, formed by the ferments, etc., we have to distill it off in the wines, and a high temperature exceeding the boiling point of water is necessary, while in other apparatus the acids are condensed, if they have been evaporated and returned into the dunder. It is therefore not likely that any other kind of apparatus will supercede those in use here.

[This posits the idea that because of the unique density of the wash, almost like heating candy sugar, the boiling point will be well above what a theoretical water-ethanol mixture of the same ABV. I have not seen this described elsewhere and wonder what instruments he using to take measurements. I’ll simply have to take some of my heaviest material and see what it boils at with a calibrated thermometer. Some heavy rum ferments are being distilled with final gravities well above 1.040. With an ABV of 5%, can that meaningfully push you above 100°C? How does boiling point change at 1.070? The author believes they need the pot still because they must drive off all the acids. Does experience with heavy rum not correct their way of thinking?]

The wines put as a charge in the high wine retort should be one-twelfth of the amount of wash put in the still when double retorts are used, and that of the low wine retort one-tenth. If single retort is used one-tenth of the still charge. So as to distill off the excess of acid 35% of the wash should be taken off in rum, wines, and lees, and the latter stored in a butt provided for the purpose.

[We see use of the term lees used again here that makes me think of lees from the retort (completely volatile products) and not lees as in spent yeast. This is where recycled nomenclature gets really annoying because its meaning is reliant on context that is not exactly clear and ignorant of other traditions. The lees stored in this butt may likely be recycled to a ferment at some point.]

Bad results accrue through defective apparatus. The injection pipes conducting the spirit vapour from the still into retort should be steam tight, and often examined to see if they are so. A good method is to place the hand on the retort as soon as it begins to get warm, if the upper portion gets hot sooner than the lower, it is sure indication of defect and should be immediately examined and put right.

The condition of the worm should also be ascertained by observing the indication of the hydrometer used for testing the spirit, if the density fluctuates, there is connection between the spirit inside and the water outside the worm, but sometimes a scale forms a kind of valve which prevents the water from entering, and allows the spirit to leak out, this can only be found out by testing the worm by hydraulic pressure. This latter condition can exist only for a short time as the spirit soon corrodes the scale, but a quantity of spirit will be lost before discovery, especially with a pewter worm. Owing to condensation of spirit vapour within the apparatus by sudden chill, collapse due to sudden vacuum destroys the still chiefly. A vacuum valve should be always attached to prevent this, and the makers generally do so, but as soon as they get out of order, instead of being adjusted they are taken off and the orifice soldered. This is a wrong proceeding and when such is the case the authorities in charge should have them restored and adjusted from time to time.

It is also advisable to roof in the apparatus thus securing them from the influence of rain.

On no account should a distiller be allowed to reverse a still seeing that the wines are weakened by this practice, there is no advantage in doing so, and the still may be collapsed by sudden vacuum, that may be formed by the water used for cooling down.

[I’m not completely sure what reversing a still entails. It could possibly be allowing suction at one point such as the cooling of the wash still to pull low wines backward into the wash still. This would be prevented if a vacuum was never allowed.]

The rum having been obtained by distillation is stored in butts and coloured with caramel, allowed to subside and drawn down into puncheons for shipment.

Caramel is obtained in the following manner, dry sugar or molasses is placed in a copper vessel, and a fire applied until it is sufficiently charred. The striking point arrives when a portion suspended in the rum to be colored, dissolves and flows out at right angles or horizontally before precipitating. The mass is immediately cooled down by pouring in water until ebullition ceases, and diluted with rum when cool enough. The longer it is kept the more brilliant it becomes.

Colour should always be tried before use, in a sinker or phial and on no account be put in the Butts before testing. Through carelessness or accident, it sometimes happens that the whole butt becomes cloudy. A small quantity of lime should be dissolved in a bucket of rum, and allowed to subside, and after subsidence amalgamated with the cloudy rum and neutralised with vinegar.

If this treatment will not restore brilliancy, precipitate the colour with temper lime, add vinegar to neutrality, decant from the precipitate into another butt and recolour with good caramel. The Rum loses in strength by this process but redistillation is the greater evil.

The rum butts should be perfectly air tight to prevent evaporation of the spirit stored in them and should be plugged up as soon as the rum is put in, especially when the supply of water in the tank is insufficient to cool down the spirit to proper temperature. Owing to the precipitation of impurities suspended in the color or caramel, a thick cake forms in the bottom of the rum butts, if they are, not rinsed out every time the rum is drawn off. Sometimes it is necessary to take out the heads of the Butts to remove the crust; when this condition exists the rum will never be brilliant, and even if it be clear an opaline tint will be visible.

When the fermenting space of a distillery is small in proportion to the amount of matter to be fermented loss can scarcely be prevented. In order to work up the fresh material, some of this wash is run before it has arrived at a proper stage, perhaps the wash is hurried through the mixing cistern before proper inversion and germification has been obtained and the distiller is blamed and dismissed through no fault of his own, for the fermentation is either slowed or stopped altogether, and this result is put down to neglect and acidity, while in point of fact, the wash may be perfectly healthy, and require only time, dilution and patience.

[The economics of this and their broader implications are fascinating. Many fermentation styles developed because of how molasses piled up. Cuba and Guyana produced seas of molasses and needed fast ways of processing it resulting in products that were competitive with the alternative of shipping the molasses as an export product with expensive freight. Jamaican had to produce tremendous value to justify their seemingly lackadaisical practices. This all becomes relevant again as the price of molasses ascends and supplies become scarce while freight costs increase. The stage is set for the higher value forms of rum that best compare to working with expensive substrates like malted barley or rye.]

If acidity exists it is perceptible as soon as the fermenting house is entered, and is probably due more to incompetence than carelessness.

No Manager that pretends to have a knowledge of distillation should for his own ends (viz. making a big weeks’ work in the sugar department) cause a superabundance of material to go to the distillery above the capacity of the house. He is directly responsible for the loss and in no way blameless.

HILLSIDE, [The name of the estate & distillery]
Vere, 1889. [Later a part of Clarendon]

[Wow, another first person account of Jamaican rum production enters the discourse. It is not about heavy rum but what ships can it launch?]

1 thought on “Manufacture of Rum, Jamaica, 1889.

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