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and collected, and this on re-heating with strong alkali and subsequent 

 acidification with sulphuric acid shewed presence of the fruity acid, while 

 an extraction of a fractional part of this distillate without the treatment 

 with alkali and acid left no fruity acid residue, shewing that any fruity 

 acid already present in the dunder in a free state had not escaped neu- 

 tralization by the alkali added to the dunder. I have also been able to 

 produce the fruit-ether of this acid in rum by treating it with alkali and 

 sulphuric acid which would seem to indicate that some of the salt of this 

 acid often escapes decomposition altogether. It would therefore seem 

 to be indicated that in order to decompose this " salt" into a form in 

 which it may afterwards be capable of furnishing a source of aroma that 

 the cane juice should be heated for a fairly long period at a tempera- 

 ture say not exceeding 80 Centigrade; in order to effect the preliminary 

 necessary saponification this is in many cases fulfilled by heating the juice 

 with lime in the cyphons. That the same decomposition will also take 

 place in the coppers is also evident, but if the fire is brisk the probability 

 is that a considerable portion of the salt will be driven off with the watery 

 vapour and will thus escape decomposition. So far however the fruity 

 acid will not be able to play its part in influencing the aroma, 

 it is " locked up" so to speak in the form of a lime salt, and requires an 

 acidification by sulphuric acid or by an acetic fermentation to set it free. 

 It is evident therefore that it will depend very much on the treatment 

 which the liquor subsequently undergoes in the Still House as to 

 as to whether this is done or not. If the " common or clean" (the last 

 adjective must evidently be used in a comparative sense) process is used, 

 and a quick purely alcoholic fermentation takes place, and if the liquor 

 be run, as it often is in this process before it is thoroughly dead then 

 the fruity acid will not be set free and the aroma due to the fruity acid 

 will be lost. If however the skimmings before being set up be run 

 on to a so called " dirty cistern," i.e., a cistern filled with cane trash, 

 and be there allowed to undergo a preliminary " souring," and this will 

 certainly comprehend an acetic fermentation, then the fruity acid will 

 be set free provided that the heating with lime in the Boiling House has 

 been efficiently carried out. 



It is probable also that the nature of the aroma produced will vary 

 with variations in the management of the trash cistern. Thus if the li- 

 quor already present in the trash cistern be fermented low down, that 

 is, if it contain much alcohol, and if the fruity acid be set free by a simul- 

 taneous acetic fermentation (and there is no doubt that many kinds of 

 fermentation go on at the same time in the trash cistern) it will tend 

 in its nascent form, i. e. at the moment at which it is set free, to com- 

 bine with the alcohol to form its characteristic fruit ether, whereas if little 

 or no alcohol be present it will probably come into the rum in its free 

 state and the aroma will be different. We shall also understand how if 

 the salt of the fruity acid escapes decomposition in the mixing cistern, 

 the fruit ether may still be formed by letting the liquor die down 

 in the fermenting cistern until a " creamy" head appears. The conditions 

 at the conclusion of an alcoholic fermentation are eminently favorable, 

 in tropical countries, to an acetic fermentation, which then plays the 

 part I have indicated. I have on several occasions microscopically ex- 

 amined these creamy heads and find them to be largely composed of 

 acetic acid bacteria. It is evident also that if the trash cistern is to 



