Note 46 — Chapter III · On the Origin of Ferments properly so called.

Here we had to seek for a most minute quantity of alcohol, that no alcoholometer could have indicated. A certain sign of the presence of alcohol is contained in the first few drops distilled; these always assume the form of little drops or striæ or, better still, oily tears, when alcohol is present in the distillate. The distillation should be effected with a small long-necked retort and a Liebig’s condenser. We must carefully watch the neck of the retort at the moment of boiling; should the liquid contain 1/1000 part of its volume of alcohol, we shall observe the indications given above for a short, but appreciable time. 1/10,000 of alcohol is difficult to judge, but with care and practice we may do it without failing. Collecting a third of each distillate, and supposing the limit of appreciation to stop at thousandths, in three distillations we may easily detect the presence of 1/10,000 of 1 c.c. of alcohol in a total volume of 100 c.c.