must be devoted to
its technology.

Aniline, toluidine, and similar bases can be methylated by the action of
methyl iodide, but the cost of iodine is too great to enable this process
to be used by the manufacturer. Methyl chloride, however, answers equally
well, and this compound, which is a liquid of very low boiling point (-23 deg.
C.), is prepared on a large scale from the waste material of another
industry, viz. the beet-sugar manufacture. It is interesting to see how
distinct industries by chemical skill are made to act and react upon one
another. Thus the cultivation of the beet, as already explained, is
largely dependent on the supply of ammonia from gas-liquor. During the
refining of the beet-sugar, a large quantity of uncrystallisable treacle
is separated, and this is fermented for the manufacture of alcohol. When
the latter is distilled off there remains a spent liquor containing among
other things potassium salts and nitrogenous compounds. This waste liquor,
called "vinasse," is evaporated down and ignited in order to recover the
potash, and during the ignition, ammonia, tar, gas, and other volatile
products are given off. Among the volatile products is a base called
trimethylamine, which is a derivative of ammonia; the salt formed by
combining trimethylamine with hydrochloric acid when heated gives off
methyl chloride as a gas which can be condensed by pressure.

Here we have a very pretty cycle of chemical transmigration. The nitrogen
of the coal plants, stored up in the earth for ages, is restored in the
form of ammonia to the crops of growing beet; the nitrogen is made to
enter into the composition of the latter plant by the chemico-physiological
process going on, and the nitrogenous compounds removed from the plant and
heated to the point of decomposition in presence of the potash (which also
entered into the composition of the plant), give back their nitrogen
partly in the form of a base from which methyl chloride can be obtained.
The latter is then made to methylate a product, aniline, derived indirectly
from coal-tar. The utilisation of the "vinasse" for this purpose was made
known by Camille Vincent of Paris in 1878.

The methylation of aniline can obviously be carried out by the foregoing
process only when beet-sugar residues are available. There is another
method which is more generally used, and which is interesting as bringing
in a distinct branch of industry. The same result can, in fact, be a