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acid. This last also served as a control experiment, as it might be ar- 

 gued, that should any aroma be produced in No. I sample, it might have 

 been caused, not by the treatment with an alkali, but to the subsequent 

 liberation of aromatic vegetable acids, or volatile vegetable acids, capable 

 of forming fruit ethers perhaps by the stronger acid sulphuric* I must 

 add that in order to preclude the possibility of action of germs other 

 than No. 18 yeast, which would of course be naturally present in the 

 cane juice, that the three portions of liquid were sterilised before 

 being fermented. No. I. was sterilised (boiled) after the treatment 

 with lime, in order to imitate the treatment to which the skimmings 

 are subjected in the boiling house, and the sulphuric acid added 

 just before the fermentation. No. III. was boiled before the treatment 

 with sulphuric acid in order that if volatile acid should be liberated 

 that they should not be driven off by the heating, that is that the 

 maximum effect if any, due to their presence, should be obtained. No. II. 

 sample was of course simply boiled without any addition. After these 

 three samples had been boiled and allowed to stand in contact with 

 sterilised air for a sufficient length of time, an equal quantity of No. 18 

 yeast, in a state of absolute purity was added to each portion and the 

 liquid allowed to ferment, the outside temperature being the same 

 in each case, In No. I. sample, which had undergone the treatment with 

 lime, the characteristic aroma was developed. In samples II. and III. 

 the aroma was not developed. It is but fair to state that the aroma 

 produced was not very strong, but there was no denying its presence. 

 Here then we have the four factors necessary for the production of the 

 aroma in question. First the germ, No. 18 yeast; secondly, the 

 medium skimmings or cane juice ; thirdly, the treatment of the liquid 

 — heating with caustic lime, or caustic alkali ; fourthly, the question of 

 time — the wash must stand 24 to 36 hours after fermentation has been 

 completed. Be it borne in mind that the absence of any one of these 

 4 factors, will result in the non-production of the aroma in question. 

 I expressly state here of the " aroma in question" because it is not con- 

 tended that no other aroma can be produced by any other germ or germs 

 which may be active in the fermentations. Indeed the treatment with lime 

 for reasons which I shall show at another time, has an effect upon the 

 flavour of the resulting spirit, independent of the action of any particular 

 germ In order however to make quite sure that the activity of 18 

 yeast is necessary in treated cane juice to ensure the production of the 

 aroma, treated cane juice was fermented by several other J amaica yeasts, 

 but no aroma was produced. My researches hitherto have been directed 

 to show that a certain aroma can be produced by a particular type or 

 variety of yeast, which cannot be produced by other germs in my pos- 

 session, but that though the activity of this yeast is essential, certain 

 other conditions are equally essential. In other words the aroma 

 produced during fermentation is the resultant of more than one force, 

 but that the type of yeast employed plays a very important part in 

 the matter and the probability is that this remark applies to any 

 other aroma produced during fermentation. I have in this case been 

 able to isolate and identify these forces, which is advantageous as shew- 

 ing how No. 18 yeast may be employed to produce the aroma, with its 

 maximum effect. But it will be seen that so far I have touched on the 

 matter somewhat superficially. I have yet to shew what is the substance 



