422 YEAST 



carbonic acid, and in the alcohol. And then came that great 

 chemist Lavoisier, and he examined into the subject care- 

 fully, and possessed with that brilliant thought of his which 

 happens to be propounded exactly apropos to this matter of 

 fermentation that no matter is ever lost, but that matter 

 only changes its form and changes its combinations he 

 endeavoured to make out what became of the sugar which 

 was subjected to fermentation. He thought he discovered 

 that the whole weight of the sugar was represented by the 

 weight of the alcohol produced, added to the weight of the 

 carbonic acid produced ; that in other words, supposing this 

 tumbler to represent the sugar, that the action of fermenta- 

 tion was as it were the splitting of it, the one half going away 

 in the shape of carbonic acid, and the other half going 

 away in the shape of alcohol. Subsequent inquiry, careful 

 research with the refinements of modern chemistry, have 

 been applied to this problem, and they have shown that 

 Lavoisier was not quite correct ; that what he says is quite 

 true for about 95 per cent, of the sugar, but that the other 

 5 per cent., or nearly so, is converted into two other things ; 

 one of them, matter which is called succinic acid, and the 

 other matter which is called glycerine, which you all know 

 now as one of the commonest of household matters. It may 

 be that we hav& not got to the end of this refined analysis 

 yet, but at any rate, I suppose I may say and I speak with 

 some little hesitation for fear my friend Professor Roscoe 

 here may pick me up for trespassing upon his province but 

 I believe I may say that now we can acount for 99 per cent, 

 at least of the sugar, and that that 99 per cent, is split up into 

 these four things, carbonic acid, alcohol, succinic acid, and 

 glycerine. So that it may be that none of the sugar what- 

 ever disappears, and that only its parts, so to speak, are 

 re-arranged, and if any of it disappears, certainly it is a very 

 small portion. 



Now these are the facts of the case. There is the fact of 

 the growth of the yeast plant ; and there is the fact of the 

 splitting up of the sugar. What relation have these two 

 facts to one another ? 



For a very long time that was a great matter of dispute. 

 The early French observers, to dO"them justice, discerned 

 the real state of the case, namely, that there was a very close 

 connection between the actual life of the yeast plant and this 

 operation of the splitting up of the sugar ; and that one 

 was in some way or other connected with the other. All 



