ty of 7-1/2 deg. Tw. (5 deg.
B.), is removed to a receptacle for subsequent neutralisation with milk
of lime, and, after the separation of sludge, is ready for
concentration.

The fatty acids remaining in the vat are boiled with a small quantity
(0.05 per cent., or 1/10 of the Twitchell reagent requisite) of
commercial barium carbonate, previously mixed with a little water; the
boiling may be prolonged twenty or thirty minutes, and at the end of
that period the contents of the vat are allowed to rest; the water
separated should be neutral to methyl-orange indicator.

It is claimed that fatty acids so treated are not affected by the air,
and may be stored in wooden packages.

_Hydrochloric Acid._--Lewkowitsch (_Journ. Soc. Chem. Ind._, 1903, 67)
has carried out a number of experiments on the accelerating influence of
hydrochloric acid upon the hydrolysis of oils and fats, which show that
acid of a specific gravity of 1.16 has a very marked effect on most
oils, cocoa-nut, cotton-seed, whale and rape oils, tallow and lard being
broken up into fatty acid and glycerol to the extent of some 82-96 per
cent. after boiling 100 grams of the oil or fat with 100 c.c. of acid
for twenty-four hours. The maximum amount of hydrolysis was attained
with cocoa-nut oil, probably owing to its large proportion of the
glycerides of volatile fatty acids. Castor oil is abnormal in only
undergoing about 20 per cent. hydrolysis, but this is attributed to the
different constitution of its fatty acids, and the ready formation of
polymerisation products. Experiments were also made as to whether the
addition of other catalytic agents aided the action of the hydrochloric
acid; mercury, copper sulphate, mercury oxide, zinc, zinc dust,
aluminium chloride, nitrobenzene and aniline being tried, in the
proportion of 1 per cent. The experiments were made on neutral lard and
lard containing 5 per cent. of free fatty acids, but in no case was any
appreciable effect produced.

So far this process has not been adopted on the practical scale, its
chief drawback being the length of time required for saponification.
Undoubtedly the hydrolysis would be greatly facilitated if the oil and
acid could be made to form a satisfactory emulsion, but although saponin
has been tried for the purpose, no means of attaining this object has
yet been devised.

_Sulphurous Acid or Bisulphite._--The use of these substances has been
patented by Stein, Berge and De Roubaix (Ger