SOLVENTS AND DILUENTS 213
It is a straw-colored, viscous liquid, with a faint odor of ammonia, and in some
respects it combines the properties of that material and glycerine. It is highly
hygroscopic and miscible with water in all proportions. It mixes with alcohol but
not with petroleum or coal-tar hydrocarbons. Like ammonia, it combines with
acids and acidic materials, forming soaps of low alkalinity with fat. It is less
alkaline, however, than ammonia, the pH of a 25 per cent solution being 11.2
at 25°C, Small additions of triethanolamine can produce stable water emulsions
of various oils and waxes. Usually the amount of triethanolamine is 2 to 4 per cent
of the oil or fat to be emulsified. Casein is colloidally dispersed in water by a 5 to
15 per cent solution of triethanolamine.
Turpentine. The name (terebinthos [GrJ, terebenthlne [Fr.]) was originally
applied to the crude exudation or balsam from various species of pine, and is still
given to certain kinds like Venice turpentine from the European larch, and Stras-
bourg turpentine from the European white fir. In the United States, however, the
word is commonly used only for the volatile liquid obtained by the destructive
distillation of an oleoresin. About two thirds of the world's supply comes from the
long-leaf pine that is grown in Georgia and the Carolinas, though part is from
other closely related species. A fair amount is from the Maritime pine cultivated
along the southwest coast of France. American production began at the close of
the XVI century. The French did not start until the middle of the XIX century,
but, until recently, their production methods were more efficient. Small amounts
of turpentine come from Spain, Greece, and other countries.
In the usual method of collecting the resinous exudate, the tree is chipped
near the base, gutters are attached, and the material is caught in earthenware
cups. (For details, see T. Hedley Barry, 'Natural Varnish Resins [London:
Ernest Benn Ltd, 1932], pp. 145-199.) The crude oleoresin (French) yields 18
per cent turpentine, 75 per cent dry resin, 10 per cent water, and 2 per cent solid
impurities. It is put into copper stills together with water in order to effect
steam distillation, the water being later separated by gravity. With methods
developed during recent years, the yield from the crude material is 15 to 25 per
cent by weight. The molten residue is rosin or colophony. Most of the distillate is
sold to the paint and varnish trade after a simple purification by redistillation
(rectification) under the name, 'pure gum spirits of turpentine,' or 'oil of tur-
pentine/
The distilled turpentine is a mixture mainly of various and closely related
aromatic hydrocarbons known as terpenes, all of which have the empirical formula,
CioHifi. The composition includes a-pinene, /?-pinene, dipentene, terpinene,
borneol, fenchyl alcohol, limonene, and traces of camphor. The American turpen-
tine is largely a- or dextro-pinene, and the French is #- or laevo-pinene.
When fresh and pure, turpentine is a clear, volatile, flammable liquid which
boils in the range of 150 to i8o°C. Any marked deviation from this range indicates
impurity, and the Federal Specifications Board specifications require that 90