Spirits Of Turpentine is obtained from the resinous sap of several varieties of pine trees. The domestic supply comes from the southern pine, which grows profusely in all the south Atlantic and Gulf Coast States. The trees are boxed in March or April, that is, V shaped apertures are cut in the trunk, so made as to retain the sap, or oleo resin as it exudes. The resin is dipped up from time to time, and when sufficient is collected, it is placed in a copper still of large capacity. When heated, the turpentine is distilled off with water which is gradually introduced into the still to regulate the temperature. The resulting distillate separates into two layers, the lower one water on which the turpentine floats as the upper layer. Turpentine has drying or oxidizing properties to a marked extent, and for this reason, is an excellent thinner for paints and varnishes. On account of this property it has a tendency to bleach or lighten paint or varnish as it dries, whereas, in using benzine for the same purpose, in fact, any of the lighter mineral spirits, yellowness is sure to follow either in white paint or varnish. Turpentine is used in all the better grades of oil varnishes, in the rubber industries and recently in the production of camphor. It is often grossly adulterated with benzine, kerosene, coal-tar naptha, rosin spirit and similar substitutes.

The specific gravity of turpentine is 0.864 to 0.868. By taking the specific gravity you can readily discover the purity. A simple test is to moisten a piece of white paper with the sample to be tested. If pure, it will entirely evaporate and leave no residue, while if kerosene, mineral oil, or rosin is present, an oily residue remains.

Let a small quantity evaporate in a cup. Rosin oil will remain as a sticky deposit and when ignited give the odor of rosin.

Concentrate by partial evaporation a small quantity of turpentine and note the odor of the concentrate. If petroleum is present, it can be detected in this way. Fill two deep glass vessels, one with pure, the other with the suspected sample. Hold the vessels over a piece of black paper and look directly down into the liquid. Petroleum or benzine is indicated by a blueish yellow bloom or cloud.

Shake the sample in a small bottle; if pure, the bubbles formed should at once disappear. The specific gravity is also changed by adulteration.

Ten barrels of crude turpentine produce two barrels of turpentine spirits and six barrels of rosin. Bear in mind that turpentine assists paint and varnish to dry, while benzine and other light mineral oils, having no oxidizing properties, cause paint and varnish to dry more slowly and tend to produce yellowness.

The residue in the turpentine still is common rosin or colophony; this varies in color from transparent white to almost black. The first season's crop of rosin is pale. Each succeeding year that the trees are tapped the rosin residue becomes darker. The trees seldom admit of tapping for more than four or five successive seasons.

Careful methods in the process of distillation will produce a lighter rosin than otherwise, in particular, if pains are taken not to push the distillation too far, but rather to allow a little turpentine to remain behind with the rosin.

Rosin is graded according to its color. The usual brands are:

WW ................ Water White

WG................Window Glass

N...................... Very Pale

M.....................................................Pale

K.......................Low Pale

I..................... Extra No. 1

H............... Standard or No. 1

F..................Extra, No. 2

E.................Standard, No. 2

D.............. Extra Strained

C.................. Dark Strained

B................. Black Strained

A....................................................Black.

All these grades are strained, freed from dirt and impurities, except the A grade.