o 30 c.c. of a 10 per
cent. solution of caustic potash. The flask is connected with a long
reflex condenser, and is also fitted with a dropping funnel containing a
solution of bromine in potassium bromide (200 grms. of Br and 250 grms. of
KBr to 1 litre of water). The bromine solution is allowed to flow into the
mixture until it has acquired a faint yellow tinge, the flask and its
contents being then heated on the water bath at about 70 deg. C. for half-an-
hour. Bromine solution is added drop by drop until the slight coloration
is permanent, excess of bromine being got rid of by boiling for a minute
or two with a little more caustic potash. The mixture is then distilled
until the distillate is free from bromoform, halogen being tested for in
the usual manner. Water is added to the contents of the flask if
necessary. It may be here observed that no acetone can be detected in the
distillate by means of the mercuric oxide test, and free bromine is also
absent. The condenser having been washed out with a little alcohol, in
order to remove any traces of bromoform which may have collected, the
distillate and washings are mixed with 50 c.c. of alcohol and sufficient
solid caustic potash to make an approximately 10 per cent. solution. The
mixture is then heated on the water bath under a reflux condenser until
the bromoform is completely decomposed. This generally occupies about
three-quarters of an hour. The liquid is allowed to cool, evaporated to
smaller bulk if necessary, and exactly neutralised with dilute nitric
acid. It is then diluted with water to 500 c.c., and an aliquot part
titrated with N/10 silver nitrate solution, using potassium chromate as
indicator; 240 parts of bromine correspond to 58 parts of acetone. The
complete analysis can be performed in one and a half to two hours. It is
imperative that the bromine used should be pure, as crude bromine
frequently contains bromoform. The method is suitable for the estimation
of acetone in wood-spirit, the spirit being diluted to 10 times its
volume, and 5 c.c. of this solution employed for the determination. For
example--

(1.) Three c.c. of a solution containing 9.61 per cent. acetone gave
1.7850 grm. KBr. Acetone found = 9.66 per cent.

(2.) Ten c.c. of a solution containing 0.96 per cent. acetone gave 0.5847
grm. KBr. Acetone found = 0.95 per cent.

~Nitro-Cotton.~--The first thing upon opening a case of wet cotton, or in
receiving a sample from the "poacher," tha