Dr. Pereira's Elements of materia medica and therapeutics : abridged and adapted for the use of medicine and pharmaceutical practitioners and students and comprising all of the medicines of the British Pharmacopœia, with such others as are frequently ordered in prescriptions or required by the physician / edited by Robert Bently and Theophilus Redwood.

  • Jonathan Pereira
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: Dr. Pereira's Elements of materia medica and therapeutics : abridged and adapted for the use of medicine and pharmaceutical practitioners and students and comprising all of the medicines of the British Pharmacopœia, with such others as are frequently ordered in prescriptions or required by the physician / edited by Robert Bently and Theophilus Redwood. Source: Wellcome Collection.

    1070/1132 (page 1038)
    [§ Cera Alba. White Wax. Yellow wax, bleached by exposure to moisture, air, and light.] Wax Bleaching.—This is effected by melting yellow wax, either in a copper vessel, or in a large vat or tub, by means of steam, running it off, while in the melted state, into a trough, called a cradle, perforated at the bottom with holes, and placed over a large water- tank, at one end of which is a revolving cylinder almost wholly immersed in water. By this means the wax is solidified, converted into a kind of ribbon, and conveyed on the surface of the water to the other end of the tank. These ribbons of wax are here lifted out, and carried in baskets to the bleaching grounds, where they are exposed to the air for one or two weeks (according to the state of the weather), being turned every day, and watered from time to time. The wax is then re-melted, re-ribboned, and re-bleached ; it is subsequently refined by melting in water acidulated with sul- phuric acid. General Characters.—It is never perfectly white, but has always a yellowish tinge. It is hard, translucent, brittle, not unctuous to the touch, does not melt under 150°, its specific gravity is about 0*965, it is inodorous, or nearly so, and without taste. The cir- cular cakes of commerce frequently contain spermaceti, which the dealers add to improve the colour. Composition.—Wax is a compound of three substances—myricin, cerin, and cerolein; which are separable from each other by boiling in alcohol, in which the myricin is insoluble, and from which the cerin crystallises by cooling, while the cerolein remains in solution. Myricin (C46H9202).—It fuses at 149° F. According to Brodie it forms 73 per cent, of the wax. It is not saponifiable by potash. Cerin (C54H10802).—It fuses at 143^° F. It constitutes about 22 per cent, of wax. It dissolves in 16 parts of boiling alcohol. By saponification with potash it yields margaric acid, a minute portion of oleic acid, and a considerable quantity of a non-saponifiable fat. Cerolein constitutes about 5 per cent, of wax. Physiological Effects and Uses.—Wax is an emollient and demul- cent. It has been administered internally, in the form of emulsion (prepared with melted wax and soap, yolk of eggs, or mucilage), in diarrhoea and dysentery, especially when ulceration of the alimentary canal is suspected. Its principal use, however, is for external appli- cation, sometimes as a mild sheathing or protecting application, some- times as a basis for the application of other agents. Pharmaceutical Uses.—White Wax is contained in'blistering paper, compound ointment of subacetate of lead, spermaceti ointment, and in. the four suppositories of the British Pharmacopoeia.