Alizarine is a substance contained in the madderroot, and largely used in dyeing reds of various shades, as Turkey red, etc. Formerly madderroot was largely employed as a dye-stuff, its capability of dyeing being chiefly due to the presence in it of alizarine; but the use of the root has been almost superseded by the employment of alizarine itself, prepared artificially from one of the constituents of coal-tar. It forms yellowish-red prismatic crystals, nearly insoluble in cold, but dissolved to a small extent by boiling water, and readily soluble in alcohol and ether. It possesses exceedingly strong tinctorial powers. Research Alizarine
Anthracene is a complex hydrocarbon contained in coal-tar, and obtained from the highest-boiling portion of the tar,
namely the so-called 'green grease', which forms the last portion of the heavy oil or dead oil resulting in the fractional distillation of the tar. Anthracene is a commercial product of some importance, as a source of alizarine and numerous other dyes of a similar kind. The commercial product forms a hard crystalline cake containing some 50 percent of anthracene; when pure it crystallizes in the form of glistening, white plates showing a bluish-violet fluorescence, and has neither taste nor smell. Several colours used in dyeing are known as 'anthracene colours'. Research Anthracene
Coal-tar or gas-tar is a thick black viscous liquid produced by the destructive distillation of coal for the manufacture of illuminating gas, consisting principally of oily hydrocarbons. It passes over with the gas into the condensers along with ammonia liquor, but being heavier than the latter, it is easily separated from it when the whole is allowed to stand. It was formerly of comparatively little use; but ince the 19th century a great number of valuable products have been derived from it by distillation, such as ammonia, naphtha, creasote, carbolic acid, and benzene, while it is also the source of the whole series of aniline colours, and other dyes, of alizarine, salicylic acid, etc. Research Coal-tar
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Matt and Leela Probert
Abbreviations
Research Alizarine
