undance and the character of
these little germs. Moreover, when a finished beer of good quality loses
after a time its agreeable flavor and becomes sour, it can be easily
shown that the alcoholic yeast deposited in the bottles or the casks,
although originally pure, at least in appearance, is found to be
contaminated gradually with these filiform or other ferments. All
this can be deduced from the facts already given, but some critics may
perhaps declare that these foreign ferments are the consequences of the
diseased condition, itself produced by unknown causes.

"Although this gratuitous hypothesis may be difficult to uphold, I will
endeavor to corroborate the preceding observations by a clearer method
of investigation. This consists in showing that the beer never has any
unpleasant taste in all cases when the alcoholic ferment properly so
called is not mixed with foreign ferments; that it is the same in
the case of wort, and that wort, liable to changes as it is, can be
preserved unaltered if it is kept from those microscopic parasites which
find in it a suitable nourishment and a field for growth.

"The employment of this second method has, moreover, the advantage of
proving with certainty the proposition that I advanced at first--namely,
that the germs of these organisms are derived from the dust of the
atmosphere, carried about and deposited upon all objects, or scattered
over the utensils and the materials used in a brewery-materials
naturally charged with microscopic germs, and which the various
operations in the store-rooms and the malt-house may multiply
indefinitely.

"Let us take a glass flask with a long neck of from two hundred and
fifty to three hundred cubic centimetres capacity, and place in it some
wort, with or without hops, and then in the flame of a lamp draw out the
neck of the flask to a fine point, afterwards heating the liquid until
the steam comes out of the end of the neck. It can then be allowed to
cool without any other precautions; but for additional safety there
can be introduced into the little point a small wad of asbestos at the
moment that the flame is withdrawn from beneath the flask. Before thus
placing the asbestos it also can be passed through the flame, as well as
after it has been put into the end of the tube. The air which then first
re-enters the flask will thus come into contact with the heated glass
and the heated liquid, so as to destroy the vitality of any dust germs
tha