TAPTI, a river of Bombay, India; ris ing in the Betus district of the Central Provinces, and flowing 450 miles W. through the Satpura uplands and the dis tricts of Candeish and Surat to the Gulf of Cambay; 17 miles below the town of Surat. Even small vessels of 40 to 50 tons burden cannot ascend higher than Surat. The port of Suwali at the mouth is now deserted, and the lower channels of the river are being silted up.
TAR, a product of the destructive dis tillation of various organic substances; but the tars of commerce are obtained 1st from the distillation of coal, etc., for gas (gas tar or coal tar), and 2d from the distillation of wood (wood tar). Gas or coal tar, which was formerly regarded as a troublesome and almost useless by product of the gas manufacture, is now a substance of so much value that it is second only in importance to the gas itself. Its value has arisen almost en tirely from the fact that it is the source of the wide range of important dyeing substances, which, derived from aniline, phenol (carbolic acid), and anthracene respectively, may all be classed as tar colors. Coal naphtha obtained by distil lation from coal tar is a mixture of sev eral hydrocarbons of different degrees of volatility, the lightest being benzol and toluol, and the earlier part of the dis tillate is composed of a mixture of these two, and that part is utilized for the preparation of aniline as the basis of the aniline colors. The material remaining
in the retort after the light oils are dis tilled over constitutes artificial asphalt, but this on further distillation at a higher heat gives off "heavy oils," leav ing in the retort pitch, a substance which when cold is hard, black, and shining, and breaks with a glassy fracture. The principal constituents of the heavy oil are carbolic acid (phenol), cresylic acid (cresol), and in the later stages of the distillatory process anthracene is ob tained. All these substances are indus trially important.
Wood tar is obtained as a by-product in the destructive distillation of wood for the manufacture of pyroligneous acid (wood vinegar), and methyl alcohol (wood spirit). Wood tar has several constituents in common with coal tar; its most characteristic fluid ingredients being hydrocarbons with methylic acetate, acetone, eupione, and creosote, with solid resinous matters, paraffin, anthracene, chrysene, etc. It possesses valuable an tiseptic properties, chiefly owing to the creosote it contains, whence its principal value for most purposes is derived. In addition to its various uses in the arts of coating and preserving timber and iron in exposed situations, and for im pregnating ships' ropes and cordage, it has various applications for external use in medicine owing to its antiseptic prop erties.