Pitch (Gr. ), a black resinous substance, commonly known as black pitch, constituting the residuum when the volatile portions of tar are driven off by heat. It is soft and sticky when warm, but becomes solid and brittle when cold. It is one of the products of the pine tree classed in commerce as naval stores, and is largely used in ship building to pay the seams and thus render them impervious to water. For this purpose it is mixed with a small portion of oil, to render it less brittle. It is also used in medicine as a mild stimulant and tonic, and is administered in pills for cutaneous diseases and for piles. In Europe pitch is manufactured chiefly from the tar produced in northern regions from pinus sylvestris (Linn.) and P. Ledebourii (Endl.) or larix Siberica (Ledeb). These trees form the vast forests of arctic Europe and Asia. The pitch used in this country is all made from the distillation of tar furnished by various species of pine, especially pinus palmtris of the southern states, from which immense quantities are prepared in North Carolina and the southern parts of Virginia. In New Jersey, New England, and Pennsylvania west of the Alleghany mountains, tar and pitch are made from pinus rigida, or pitch pine, and other species. - Burgundy pitch is used for plasters, and when applied for some time to the skin acts as a rubefacient, exciting slight inflammation and serous effusion, and relieving chronic affections of the chest and rheumatic pains.
It is prepared from the resinous matter that exudes from the Norway spruce (abies excelsa). The resin is melted in hot water, and strained through coarse cloths. Burgundy pitch is produced in Finland, the Black Forest, Austria, and Switzerland. The pure article is rather opaque, yellowish brown, hard and brittle when cold, yet gradually takes the form of the vessel in which it is kept. It has an aromatic and very agreeable odor, which is quite marked when heated; it is strongly adhesive, and breaks with a clear conchoidal fracture. Few drugs are more subject to adulteration than Burgundy pitch. The true article is seldom met with in this country, the substance usually sold here under that name being made up of various mixtures of common rosin, wax, and fatty matters. - Canada pitch resembles the preceding in its properties, and is prepared from the inspissated juice of the hemlock spruce (abies Canadensis). The juice exudes spontaneously from old hemlock trees, and hardens upon the bark, which is stripped off, broken in pieces, and boiled in water. The pitch as it rises to the surface is skimmed off, and is purified by a second boiling. It consists of resin with a little volatile oil. It melts at 198° F., and is almost too soft at the temperature of the body to be worn as a plaster.
The finer quality of Canada pitch, such as hardens in clean tears in the older trees, commands a high price, being sold under the name of " spruce gum," and is used as chewing gum. The poor grades are often sold as "hemlock gum." - The residue from the distillation of coal tar is also called pitch, and is used as a coloring ingredient of a coarse black varnish much used for protecting iron work from rust. An increase of temperature produces decomposition, with the formation of a product having the consistency of butter. - Asphalt is sometimes called mineral pitch, or Jew's pitch. (See Asphaltum).