addition of alcohol, a solution is at once obtained, and the granular
appearance disappears, and the solution becomes homogeneous. The acid
mixture and the method of nitrating have much to do with the action of the
various solvents, so also has the presence of water.

Dr Schupphaus found that propyl and isobutyl alcohols with camphor were
active solvents, and the ketones, palmitone, and stearone in alcohol
solution, also alpha- and beta-naphthol, with alcohol and anthraquinone
(diphenylene diketone) in alcoholic solution, and also iso-valeric
aldehyde and its derivatives, amyliden-dimethyl and amyliden-diethyl
ethers.

August Sayer (U.S.P., No. 470,451) finds diethyl-ketone, dibutyl-ketone,
di-pentyl-ketone, and the mixed ketones,[A] methyl-ethyl, methyl-propyl,
methyl-butyl, methyl-amyl, and ethyl-butyl ketones are active solvents of
pyroxyline; and Paget finds that although methyl-amyl oxide is a solvent,
that ethyl-amyl oxide is not.

[Footnote A: Ketones are derived from the fatty acids by the substitution
of the hydroxyl of the latter by a monad positive radical. They thus
resemble aldehydes in constitution. The best-known ketone is acetone
CH_{3}CO.CH_{3}. Mixed ketones are obtained by distilling together salts
of two different fatty acids. Thus potassic butyrate and potassic acetate
form propyl-methyl-ketone--

C(C_{2}H_{5})H_{2}
|
CO.CH_{3}]

The solvents of pyroxyline can be divided into general classes--First,