{4}. One cubic cent. of
NO equals .003805 grm. of NaNO_{3}. The insoluble matter, both organic and
inorganic, should also be determined, also sulphate of soda and lime
tested for.

~Analysis of Mercury Fulminate (Divers and Kawakita's Method).~--A weighed
quantity of mercury fulminate is added to excess, but measured quantity of
fuming hydrochloric acid contained in a retort connected with a receiver
holding water. After heating for some time, the contents of the retort and
receiver are mixed and diluted, and the mercury is precipitated by
hydrogen sulphide. By warming and exposure to the air in open vessels the
hydrogen sulphide is for the most part dissipated. The solution is then
titrated with potassium hydroxide (KOH), as well as another quantity of
hydrochloric acid, equal to that used with the fulminate. As the mercury
chloride is reconverted into hydrochloric acid by the hydrogen sulphide,
and as the hydroxylamine does not neutralise to litmus the hydrochloric
acid combined with it, there is an equal amount of hydrochloric acid free
or available in the two solutions. Any excess of acid in the one which has
received the fulminate will therefore be due to the formic acid generated
from the fulminate. Dr. Divers and M. Kawakita, working by this method,
have obtained 31.31 per cent. formic acid, instead of 32.40 required by
theory. (_Jour. Chem. Soc._, p. 17, 1884.)

Divers and Kawakita proceed thus: 2.351 grms. dissolved, as already
described, in HCl, and afterwards diluted, gave mercury sulphide equal to
70.40 per cent. mercury. The same solution, after removal of mercury,
titrated by iodine for hydroxylamine, gave nitrogen equal to 9.85 per
cent., and when evaporated with hydroxyl ammonium chloride equal to 9.55
per cent. A solution of 2.6665 grms. fulminate in HCl of known amount,
after removal of mercury by hydrogen sulphide, gave by titration with
potassium hydrate, formic acid equal to 8.17 per cent. of carbon.
Collecting and comparing with calculation from formula we get--

Calc. I. II. III.

Mercury 70.42 70.40 ... ...
Nitrogen 9.86 9.85 9.55 ...
Carbon 8.45 ... ... 8.17
Oxygen 11.27 ... ... ...
_______

100.00

~The Analysis of Cap Composition.~--Messrs F.W. Jones and F.A. Willcox
(_Chem. News_, Dec. 11, 1896) have proposed the following process for the
analysis of this substance:--Cap composition usually consis