apply precisely the same substantive name to the soul of man and to a
glass of gin! And then there is still yet one other most curious piece
of nomenclature connected with this matter, and that is the word
"alcohol" itself, which is now so familiar to everybody. Alcohol
originally meant a very fine powder. The women of the Arabs and other
Eastern people are in the habit of tinging their eyelashes with a very
fine black powder which is made of antimony, and they call that
"kohol;" and the "al" is simply the article put in front of it, so as to
say "the kohol." And up to the 17th century in this country the word
alcohol was employed to signify any very fine powder; you find it in
Robert Boyle's works that he uses "alcohol" for a very fine subtle
powder. But then this name of anything very fine and very subtle came
to be specially connected with the fine and subtle spirit obtained from
the fermentation of sugar; and I believe that the first person who
fairly fixed it as the proper name of what we now commonly call spirits
of wine, was the great French chemist Lavoisier, so comparatively recent
is the use of the word alcohol in this specialised sense.

So much by way of general introduction to the subject on which I have to
speak to-night. What I have hitherto stated is simply what we may call
common knowledge, which everybody may acquaint himself with. And you
know that what we call scientific knowledge is not any kind of
conjuration, as people sometimes suppose, but it is simply the
application of the same principles of common sense that we apply to
common knowledge, carried out, if I may so speak, to knowledge which is
uncommon. And all that we know now of this substance, yeast, and all
the very strange issues to which that knowledge has led us, have simply
come out of the inveterate habit, and a very fortunate habit for the
human race it is, which scientific men have of not being content until
they have routed out all the different chains and connections of