is
stated to be 10.62.[1]

[Footnote 1: Watts' Dict., orig. ed., v. 277.]

I believe these determinations to be exact for the specimens employed.
But the condition of aggregation may not improbably vary somewhat in
different specimens. It seems, however, clear that these forms of
silver have a lower specific gravity than the normal, and this is what
would be expected.

Chestnut Hill, Philadelphia, May, 1889.

--_Amer. Jour. of Science._

* * * * *

TURPENTINE AND ITS PRODUCTS.[1]

[Footnote 1: Read at a meeting of the Liverpool Chemists'
Association.]

By EDWARD DAVIES, F.C.S., F.I.C.

In treating this subject it is necessary to limit it within
comparatively narrow bounds, for bodies of the turpentine class are
exceedingly numerous and not well understood. In this definite class
turpentine means the exudation from various trees of the natural order
Coniferae, consisting of a hydrocarbon, C10 H16, and a resin. The
constitution of the hydrocarbons in turpentine from different sources,
though identical chemically, varies physically, the boiling point
ranging from 156 deg. C. to 163 deg. C., the density from 0.855 to 0.880, and
the action on polarized light from -40.3 to +21.5. They are very
unstable bodies in their molecular constitution, heat, sulphuric acid,
and other reagents modifying their properties. The resins are also
very variable bodies formed probably by oxidation of the hydrocarbons,
and as this oxidation is more or less complete, mixtures are formed
very difficult to separate and study.

Turpentine as met with in commerce is mainly derived from _Pinus
maritima_, yielding French turpentine, and _Pinus australis_,
furnishing most of the American turpentine. The latter is obtained
from North and South Carolina, Georgia and Alabama. In Hanbury and
Fluckiger's Pharmacographia there is a full description of the manner
in which the trees are wounded to obtain the turpentine. Besides these
there are Venice turpentine from the larch, _Pinus Larix_, Strassburg
turpentine from _Abies pectinata_, and Canada balsam from _Pinus
balsamea_.

The crude American turpentine is a viscid liquid of about the
consistence of honey, but varying to a soft solid, known as gum, thus,
according to the amount of exposure which it has undergone, it
contains about 10 to 25 per cent. of "spirits," to which the name of
turpentine is commonly given, the rest being resin, or as it i