ce
of air many bacteria promote hydrolysis, under favourable conditions as
to temperature and access of oxygen, the process going beyond the simple
splitting up into fatty acid and glycerol, carbon dioxide and water
being formed. Under anaerobic conditions, however, only a slight primary
hydrolysis was found to take place, though according to Rideal (_Journ.
Soc. Chem. Ind._, 1903, 69) there is a distinct increase in the amount
of free fatty acids in a sewage after passage through a septic tank.

Experiments have also been made on this subject by Rahn (_Centralb.
Bakteriol_, 1905, 422), who finds that _Penicillium glaucum_ and other
penicillia have considerable action on fats, attacking the glycerol and
lower fatty acids, though not oleic acid. A motile bacillus, producing
a green fluorescent colouring matter, but not identified, had a marked
hydrolytic action and decomposed oleic acid. The name "lipobacter" has
been proposed by De Kruyff for bacteria which hydrolyse fats.

III. _Use of Chemical Reagents._--Among the chief accelerators employed
in the hydrolysis of oils are sulphuric acid and Twitchell's reagent
(benzene- or naphthalene-stearosulphonic acid), while experiments have
also been made with hydrochloric acid (_Journ. Soc. Chem. Ind._, 1903,
67) with fairly satisfactory results, and the use of sulphurous acid, or
an alkaline bisulphite as catalyst, has been patented in Germany. To
this class belong also the bases, lime, magnesia, zinc oxide, ammonia,
soda and potash, though these latter substances differ from the former
in that they subsequently combine with the fatty acids liberated to form
soaps.

_Sulphuric Acid._--The hydrolysing action of concentrated sulphuric acid
upon oils and fats has been known since the latter part of the
eighteenth century, but was not applied on a practical scale till 1840
when Gwynne patented a process in which sulphuric acid was used to
liberate the fatty acids, the latter being subsequently purified by
steam distillation. By this method, sulpho-compounds of the glyceride
are first formed, which readily emulsify with water, and, on treatment
with steam, liberate fatty acids, the glycerol remaining partly in the
form of glycero-sulphuric acid. The process has been investigated by
Fremy, Geitel, and more recently by Lewkowitsch (_J. Soc. of Arts_,
"Cantor Lectures," 1904, 795 _et seq._), who has conducted a series of
experiments on the hydrolysis of tallow with 4 per cent. of su