Kinds of Turpentine

Two other obvious characteristics of different samples of spirit of turpentine may now be noticed - namely, odour and boiling-point. Some samples have a much more agreeable scent than others; the vapour of these seems to have a less marked tendency to produce headache than that of the pungent and cruder-smelling varieties. The range in boiling-point is not very extensive; but it may be taken as about 25° C., the figures ranging from 155° to 181.° Samples having lower boiling-points evaporate more quickly than those which enter into ebullition at higher temperatures. The solvent power on resins differs with different kinds; this is a property which is of importance in varnish-making, but very little accurate knowledge exists on this point. But there is one characteristic almost peculiar to the terpenes which must not be overlooked. When oxidizing they possess, unlike the alcohols and benzene and petroleum spirit, a power of starting or increasing the absorption of oxygen by linseed or other drying oils; in fact, they act as siccatives.

This property is constantly utilized in oil-painting; probably it is connected with the formation of hydrogen peroxide which passes on its surplus atom of oxygen to the oil present.

A few of the more important turpentine oils may now be named:

American oil, chiefly from Pinus palustris and P. Tæda.

Austrian oil, partly from Pinus Laricio, partly from P. Pumilio. Burmese oil, from Pinus Khasya. French oil, from Pinus Pinaster (= P. maritima). German oil, from Pinus sylvestris, P. Cembra, P. Abies, P. vulgaris, etc. Juniper oil, from Juniperus communis. Russian and Swedish oils, chiefly from Pinus sylvestris and P. Ledebourii. Strasburg oil, from Abies pectinata.

The above-named turpentine oils are accompanied by small amounts of various resins, camphor, and other oxygenated bodies, from which they may be separated by treatment with caustic potash, metallic sodium, and fractional distillation.