themselves. The extraction of the resin by means of alcohol--the usual
way, I believe--was a more troublesome operation than it appeared to be,
as the following experiment will show: One hundred grains of No. 8 were
taken, dried thoroughly, reduced to fine powder, and introduced into a
flask containing 4 ounces of alcohol in the form of methylated spirit,
boiled for an hour--the flask during the operation being attached to an
inverted condenser--filtered off, and the residue treated with a smaller
amount of the spirit and boiled for ten minutes. This was repeated with
diminishing quantities until in all 14 ounces had been used before the
alcoholic solution ceased to turn blue on the addition to it of strong
sulphuric acid, or failed to give a brownish precipitate with stannous
chloride. As the sample contained a considerable quantity of potassium
carbonate, in which the resin is soluble, it was thought that by
neutralizing this it might render the resin more easy of extraction.
This was found to be so, but it was accompanied by such a mass of
extractive as made it in the long run more troublesome, and hence it was
abandoned. Thinking the spirit employed might be too weak, an experiment
with commercial absolute alcohol was carried out as follows: One hundred
grains of a red sample, No. 4, were thoroughly dried, powdered finely,
and boiled in 2 ounces of the alcohol, filtered, and the residue treated
with half an ounce more. This required to be repeated with fresh half
ounces of the alcohol until in all 7½ were used; the time occupied from
first to last being almost three hours. This was considered
unsatisfactory, besides being very expensive, and so it, also, was set
aside, and a series of experiments with methylated spirit alone was set
in hand. The results showed that the easiest and most satisfactory way
was to take 100 grains (this amount being preferred, as it reduces error
to the minimum), dry thoroughly, powder finely, and macerate with
frequent agitation for twenty-four hours in a few ounces of spirit, then
to boil in this spirit for a short time, filter, and repeat the boiling