W. M. Hamlet, in a paper before the London Chemical Society, said:
Flasks similar to those of Pasteur ("Etudes sur la Biere," p. 81),
holding about ¼ liter, were used. The liquids employed were Pasteur's
fluid with sugar, beef-tea, hay infusion, urine, brewers' wort, and
extract of meat. Each flask was about half filled, and boiled for ten
minutes, whereby all previously existing life was destroyed. The flask
was then allowed to cool, the entering air being filtered through a plug
of glass wool or asbestos. The flask was then inoculated with a small
quantity of previously cultivated hay solution or Pasteur's fluid.
Hydrogen, oxygen, carbonic oxide, marsh-gas, nitrogen, and sulphureted
hydrogen, were without effect on the bacteria. Chlorine and hydric
peroxide (about 7 per cent, of a 5 vol. solution) were fatal to
bacteria. The action of various salts and organic acids in 5 per cent,
solution was tried. Many, including potash, soda, potassic bisulphite,
sodic hyposulphite, potassic chlorate, potassic permanganate, oxalic
acid, acetic acid, glycerin, laudanum, and alcohol, were without effect
on the bacterial life. Others--the alums, ferrous sulphate, ferric
chloride, magnesic and aluminic chlorides, bleaching powder, camphor,
salicylic acid, chloroform, creosote, and carbolic acid--decidedly
arrested the development of bacteria. The author has made a more
extended examination of the action of chloroform, especially as regards
the statement of Müntz, that bacteria cannot exist in the presence of
2½ per cent, of chloroform, which substance is therefore useful in
distinguishing physiological from chemical ferments. The author
concludes that amounts of chloroform, phenol, and creosote, varying from
¼ to 3 per cent., do not destroy bacteria, although their functional
activity is decidedly arrested while in contact with these reagents. To
use the author's words, bacteria may be pickled in creosote and carbolic
acid without being deprived of their vitality. The author concludes that
the substances which destroy bacteria are those which are capable of
exerting an immediate and powerful oxidizing action, and that it is
active oxygen, whether from the action of chlorine, ozone, or peroxide
of hydrogen, which must be regarded as the greatest known enemy to
bacteria.
Mr. Hamlet, in replying to some remarks of Messrs. Kingzett and
Williams, said that in all cases the solution which he had used had
been completely sterilized by exposure to a temperature of 105° for ten
minutes. The India-rubber tubing he had used was steamed. Carbolic acid
solution must contain at least 5 per cent, of carbolic acid to be fatal
to bacteria. He was quite aware of the importance of distinguishing
between the action of the substances on various kinds of bacteria, and
was quite prepared to admit that a treatment which would be fatal to one
kind of bacterium might not injure another.
* * * * *