The Natural Organic Colouring Matters
By
Arthur George Perkin, F.R.S., F.R.S.E., F.I.C., professor of colour chemistry and dyeing in the University of Leeds
and
Arthur Ernest Everest, D.Sc., Ph.D., F.I.C., of the Wilton Research Laboratories; Late head of the Department of Coal-tar Colour Chemistry; Technical College, Huddersfield
Longmans, Green and Co.
39 Paternoster Row, London
Fourth Avenue & 30th Street, New York
Bombay, Calcutta, and Madras
1918
Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.
Aloes consist of an exudation from the leaves of various species of aloe, which has been evaporated to dryness. The leaves of the aloe plants are fleshy and contain a bitter resinous juice, which exudes when they are cut transversely. This is collected and is allowed to dry gradually at the ordinary temperature, or more frequently is boiled until a sample on cooling sets to a solid mass. In the former case the product is opaque owing to the presence of crystals of aloin, whereas in the latter, these being absent, it is vitreous and transparent. Aloes are employed medicinally as a purgative and form one of the commonest constituents of pills and aperients generally. The chief varieties of aloes are Barbadoes aloes, A. arborescens, Socrotine aloes, A. socrotina, and Cape aloes, A. ferox, A. arborescens, A. perryi (Baker). Uganda aloes -are a variety of Cape aloes. Natal aloes are not now found in commerce. Finally, Curagoa aloes are prepared from the A. vulgaris, A. socrotina, and A. arborescens, Jafferabad aloes from A. abyssinica.
Though aloes do not appear to have been employed to any extent for dyeing purposes, they give on fabrics mordanted with aluminium and iron a nut-brown coloured shade. More useful for this purpose in the past were the products of their decomposition with nitric acid known as aloetic and chrysaminic acids, substances studied by Schunck as far back as 1841 (Annalen, 39, 5). The first attempts to apply them to fabrics were made by Boutin in 1840. Aloetic acid dyes unmordanted wool a deep brown colour, and this is brightened by a subsequent treatment of the material in a bath of stannous chloride, whereas a moss-green shade is said to be obtainable by the use of ammonium aloetate. Chrysaminic acid also dyes wool brown, and the colour is rendered more permanent by the employment of aluminium and tin mordants. The literature on aloes is exceedingly voluminous, and on this account some part of the earlier work on this subject has been omitted.
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