ACTIONS AND USES 689 



one-third of oleate, and thirty to sixty per cent, of water. 

 To make yellow soap, the ley, while being concentrated, 

 is treated with considerable quantities of resin. Many 

 soaps are now made with a large percentage of silicates. 

 Mottled and marbled soaps owe their colour to the presence 

 of a little iron. Glycerin soap, prepared by heating the soap 

 ley with water for two or three hours at 400 Fahr., contains 

 a mixture of soap and glycerin. The costly Castile and some 

 Pharmacopoeia soaps are made with purified animal fat, 

 or olive oil, and sodium or potassium hydroxide. Soft or 

 potash soaps are made by boiling seal or whale oil with 

 potassium hydroxide or carbonate, and gradually evaporat- 

 ing to the required consistence. Soaps for medicinal pur- 

 poses are now made superfatted, neutral, or alkaline, in 

 cake and powder, with admixture of carbolic acid, creolin, 

 resorcin, sulphur, menthol, eucalyptus, balsams, camphor, 

 sanitas, etc. 



Soaps have an alkaline, acrid taste, dissolve readily in 

 water and spirit, but should not impart an oily stain to 

 paper. When heated, they fuse, swell up, and leave 

 charcoal and carbonate of their alkali. Calcium and 

 magnesium salts, such as occur in hard waters, decompose 

 soap ; the fatty acids form insoluble flakes of stearate and 

 oleate of calcium and magnesium ; soap is hence used as a 

 test for the hardness of water. 



ACTIONS AND USES. Soaps contain some free alkali, and 

 hence are slightly irritant. They are mildly laxative, 

 diuretic, emetic, and antacid. They form convenient 

 adjuncts to more active laxatives or diuretics, and are 

 serviceable additions to laxative clysters. Externally, 

 they are used as stimulants, detergents, and lubricants, 

 and in pharmacy as excipients. 



Soap and warm water are in everyday use for cleansing 

 the skin, removing scurf, neutralising acrid fatty matters, 

 keeping open the orifices of sebaceous glands, promoting 

 growth of hair, as well as preparing the skin for operations, 

 blisters, and parasiticides. When erythema is produced 

 by badly-fitting harness or other causes, irritation is abated 

 by rubbing the parts with a neutral soap, and subsequently 

 dressing with vaseline, or sugar of lead lotion, or with 



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