SOAP.

337

solvent for urinary calculi. The Hon. Horace Walpole ( PhilosophicalTransactions , xlvii. 43 & 472) gained great relief from it. By theaction of lime-water on soap, an insoluble calcareous soap and a solu-tion of caustic soda are formed. As a purgative, soap is rarely exhi-bited alone: in combination with rhubarb it may be employed withconsiderable benefit in habitual constipation and disordered conditionsof the biliary functions. In the form of enema, a strong solution of soapis sometimes used with great relief to dissolve hardened faces, andrelieve obstinate constipation. As a resolvent or alterative, soap wasonce much esteemed in enlargements and -various chronic disorders ofthe viscera and glands; and as the alkalies have been found useful inthe same diseases, any good effects which may have been obtained bysoap are probably referrible to its alkaline base.

Externally, soap is frequently employed on account of its detergent,lubricating, and discutient qualities. Thus, in tinea capitis, scabies, andvarious other skin diseases, ablution night and morning with soap-watergreatly contributes to the cure. On account of its lubricating qualities,soap is a most convenient adjunct to liniments. The uses of the lini-ment, cerate, and plaster of soap, are noticed below.

Lastly, soap is useful in pharmacy to render other medicines moresoluble, or to give a proper consistence to various substances for themaking of pills. Thus it is a constituent of various pills (e. g. pil. rheicomp., pil. sap. comp., and pil. scilla comp.) In some eases it acts asI the adjuvans, assisting and promoting the operation of other medicines';as a corrigens, correcting their operation; and as a constituans, impartingan agreeable or convenient form. The addition of soap to aloes orextract of jalap is cited by Dr. Paris ( Pharmacologia ) as an instance inI which soap fulfils all three of these objects.

Aoministration.—T he usual dose of soap, taken in a pilular form, isfrom five grains to half a drachm. In cases of poisoning by the mineralacids, half a pint of a strong solution of soap should be instantly admi-nistered.

1. Linimentum Saponis, Ph . L. & D. (soap, 3iii.; camphor, 3i.;spirit of rosemary, f. 3xvi.): Tinctura Saponis Camphorata, Ph . Ed. &U.S.(soap, 3iv.; camphor, Sii.; oil rosemary, f. 3ss.; alcohol, f. Sxxxii.) Ding-gists frequently substitute soft soap (animal oil potash soap) for the oliveoil soda soap of the Pharmacopoeia . Soap liniment or opodeldoc is usedas a stimulant and discutient, as well as, on account of its lubricatingqualities, in local pains, sprains, bruises, rheumatism, &c. When mixedwith three-fourths of its volume of tincture of opium, it constitutes theanodyne liniment ( linimentum saponis cum opio, vel linimentum anodynum)of the Dublin Pharmacopoeia.

2. Ceratum Saponis, Ph . L. (soap, 3x.; w r ax, 3xiiss,; oxide of lead,powdered, 3xv.; olive oil, Oj.; vinegar, Cj.)—The subacetate of lead,formed by boiling oxide of lead with vinegar, is decomposed by the soap,the soda of which combines with the acetic acid of the subacetate, whilethe fatty acids (oleic and margaric) unite with the lead. The wax and oilserve to give consistence to the preparation. Soap cerate is used as amild cooling dressing for scrofulous swellings, and other local inflamma-tions, as well as for fractured limbs: in the latter case its principal useis as a mechanical support.

z