_Strassburg Turpentine_; F. _Térébenthine d’Alsace ou de Strasbourg_,
_Térébenthine du sapin_; G. _Strassburger Terpenthin_.
=Botanical Origin=—_Pinus Picea_ L. (_Abies pectinata_ DC.), the Silver
Fir,[2296] a large handsome tree, growing in the mountainous parts
of Middle and Southern Europe from the Pyrenees to the Caucasus, and
extending under a slightly different form (var. β. _cephalonica_) into
continental Greece and the islands of Eubœa and Cephalonia.
=History=—Belon in his treatise _De Arboribus coniferis_ (1553)
described this turpentine, which is also briefly yet accurately noticed
by Samuel Dale,[2297] a learned apothecary of London and the friend of
Sloane and Ray. It had a place in the London Pharmacopœia until 1788,
when it was omitted from the materia medica.
=Extraction=—The oleo-resin of _P. Picea_, like that of _P. balsamea_,
is contained in little swellings of the bark[2298] of young stems, and
is extracted by the tedious process of puncturing them and receiving
in a suitable vessel the one or two drops which exude from each. It is
still collected near Mutzig and Barr, in the Vosges (1878), though only
to a very small extent.
=Description=—An authentic sample collected for one of us by the
Surveyor of Forests in the Bernese Jura, Switzerland, resembles very
closely Canada balsam, but is devoid of any distinct fluorescence. It
has a light yellow colour, a very fragrant odour,[2299] more agreeable
than that of Canada balsam, and is devoid of the acrid bitterish taste
of the latter.
We found our specimen to have sp. gr. of distilled water. It deviates
a ray of polarized light 3° to the left, if examined either pure or
diluted with a fourth of its weight of benzol, in the manner described
at p. 610. Our drug is soluble in the same liquids as the Canadian, yet
is miscible with glacial acetic acid, absolute alcohol and acetone,
without leaving any considerable flocculent residue. It is even soluble
in spirit of wine, the solution being but very little turbid. The
solutions have an acid reaction.
[2294] From information obligingly communicated by Mr. N. Mercer of
Montreal and Mr. H. Sugden Evans of London.—See also _Proc. Am. Pharm.
Assoc._, 1877, page 337, abstracted in _Ph. Jour._ viii. (1878) 813.
[2295] _Proceedings of the American Pharmaceutical Association_,
Philadelphia, 1873. 119—also 1874. 433.
[2296] _Sapin_ in French; _Weisstanne_ or _Edeltanne_ in German.
[2297] _Pharmacologia_, Lond. 1693. 395.
[2298] See Morel, _Ph. Jour._ viii. (1877) 21.
[2299] Hence it is sometimes called in French _Térébenthine au citron_.
=Chemical Composition=—After the complete desiccation of a small
quantity, there remained 72·4 per cent. of a brittle, transparent
resin, soluble in glacial acetic acid, but not entirely in absolute
alcohol or in acetone. By submitting half a pound of the turpentine to
distillation with water, we obtained 24 per cent. of essential oil,
the remaining resin being when cold perfectly friable. The fresh oil,
purified by sodium, deviates the ray of polarized light to the left,
whereas the remaining resin, dissolved in half its weight of benzol,
shows a weak dextrogyre rotation. The oil boils at 163° C. After having
kept it for two years and a half in a well-stopped bottle, we find that
it has become considerably thicker and now deviates to the right. If
saturated with dry hydrochloric acid, the oil does not yield a solid
compound.
This oil has nearly the same agreeable odour as the crude oleo-resin,
yet the essential oil of the _cones_ of the same tree is still more
fragrant. The latter is one of the most powerfully deviating oils,
the rotation being 51° to the left, and it is consequently extremely
different from the oil obtained from the turpentine of the stem, though
its composition is represented by the same formula, C₁₀H₁₆.
A peculiar sugar called _Abietite_, nearly related to mannite but
having the composition C₁₂H₁₆O₆, has been detected by Rochleder[2300]
in the leaves of the Silver Fir.
=Uses=—Strassburg turpentine possesses the properties of common
turpentine, with the advantage of a very agreeable odour. It was
formerly held in great esteem, but has now become nearly forgotten.