The chief properties of the non-volatile or resinous constituents— the turpentine have already been described. ptestsa ] It now therefore remains only to notice the relations of the constituents individually, and bhortly describe their derivatives.
Turpentine Resin, as a whole, is acid, and has the composition (HO, In reality, however, it contains three distinct acids isomeric with each other, but having dissimilar physical properties ; their names are pimaric, eylvie, and pinic acids. The two latter are, no doubt, mere modifications of the first, and probably owe their dis similarity to the action of heat. Pimaric acid is best obtained from the white resin or galipot of Bordeaux turpentine. The realn is pow dered, digested in a mixture of six parts of cold alcohol and one of ether, which separates matters other than pimarie acid, and the residue is finally boiled with alcohol. On standing for a few days, the solution deposits crystalline tufts of the acid under consideration. It is very soluble In ether and hot alcohol, less so in cold alcohol. It fusee at 257° Fehr., but does not re-solidify till cooled down to 154° Fehr. The fused acid is clear and transparent as glees ; when powdered it may be perfectly dissolved in its own weight of alcohol, but Iti a few minutes the solution begins to deposit elliptical crystals, which, like tho ma imed acid, require ton times their weight of alcohol for solution. By distillation in vacuo pimaric acid furnishos sylvic acid, at first thought to be new, and called pyromeric acid. Sylvic acid may be obtained from powdered resin. The latter is well washed with cold alcohol to remove pinta acid, and the residue dissolved in boiling alcohol ; on standing, the sylvie acid crystallises out. Its crystalline character is
more pronounced than that of pimarie acid ; in other respects the two much resemble each other. Pink add, or the amorphous resin of colophouy, is obtained on evaporating the mother liquor from the pre paration of eylvic acid ; by heat it Is partially decomposed, and changed to another Isomer, colopholie add.
By destructive distillation at a low temperature, turpentine resin yields the hydrocarbons resinein or colephen and tereben already referred to. At a higher heat it gives a liquid hydrocarbon containing retinaphtha or toluen (C,„H„) [ToLupsne Gnour]; relinyl (C,„EI„), isomeric with cumen [CuisiNic Amp]; and retinal (C„,11„,1), an ino dorous and tasteless oil, of sp. gr. 0•9, and boiling-point about 460° Fahr. Retinel is a solvent of sulphur and iodine, It absorbs many times its volume of sulphurous and other gases, and is not acted upon by alkalies.
The acids of resin are monobasic, difficult to obtain in a definite crystalline state, are mostly insoluble in water, and soluble in ether. The alkaline resinates are of course true soaps, but are inferior in detergent qualities to the stearates, oleates, and margaratea.
By prolonged ebullition with strong nitric acid, turpentine resin yields AZOMARIC Acta and terebic or terebilic acid The latter is almost insoluble in cold water, moderately soluble in hot water, and readily taken up by alcohol or ether. Submitted to de structive distillation, it gives pyrutenbilic acid, a colourless oily liquid of sp. gr. Pol. and boiling-point 392' Fahr.