A Manual of the Chemistry of the Carbon Compounds

470 THE CHEMISTRY OF
NATURAL BASES OR ALKALOIDS.
Many plants, and principally those of medical or poisonous properties,
contain basic compounds which are called alkalnds. They
contain nitrogen, and a few of them are volatile, and have groat
resemblance with compound ammonias; the majority, however, have
a more complicated constitution, and are decomposed by heat.
Most of them are sparingly soluble in water, more freely in alcohol;
the solutions have an alkaline reaction, and usually an intensely
bitter taste. They combine, like ammonia, with acids, forming crystallizable
salts, which are more freely soluble than the bases. Their
hydrochlorides form, with the chlorides of gold, platinum, mercury,
&O-, crystalline double salts.
Most alkaloids are precipitated from their solutions by tannin, the
double iodides of potassium, and mercury, cadmium and bismuth,
phosphomolybdic acid, phosphoantinyonic acid, metatungstio acid,
picric acid, and a solution of iodine hi potassium iodide, By treating
these precipitates with an alkali, the bases are set free, and the above
reactions are therefore frequently made use of hi the preparation or
detection of alkaloids.
VOLATILE ALKALOIDS.
Conine CgH^N exists in all parts of the true hemlock (Goninm
maeulatitm), principally in the seeds, from which it is obtained by
distilling them with dilute soda-solution. The distillate is neutralized
with sulphuric acid, evaporated to the consistency of a syrup, and
then distilled with concentrated soda.
Conine is an oily liquid having the specific gravity 0*89, boiling at
163°*5, and taming the plane of polarization to the right. It possesses
a nauseous and sharp taste and disagreeable smell; it dissolves
to some extent in cold water, and this solution becomes turbid
on heating it gently, conine being more soluble hi cold than in warm
water. When in contact with air, it colours brown, and is slowly decomposed
with the formation of ammonia; the solutions of its salts
undergo a similar change. On oxidation it yields butyric acid, and
when nitrogen trioxide is passed into it, a yellow thick liquid is
formed, which by water is decomposed into nitric acid and azoconi/driw
C8H|6(NO)K, a pale yellow oil, which is reconverted into conine
by the action of nascent hydrogen:—
CaHM(NO)N + 2Hj » C8H,,N + HjO + NHS
When azoconydrine is heated with phosphorus pentoxide, it is resolved
into water, nitrogen, and conykne C8Hl4, which is a homologue