which are
contained in the carbonic acid, and in the alcohol. And then came that
great chemist Lavoisier, and he examined into the subject carefully,
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 carbonic acid produced;
that in other words, supposing this tumbler to represent the sugar, that
the action of fermentation 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 have 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 account for 99 per
cent. at least of the sugar, and 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 whatever 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 connect