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Show PRICKLY SALTWORT. PRICKLY SALTWORT. alcohol, as directed by the London college, is to discoverif any pure carbonate of potash, dissolved in six times iis weicht of 206 ofthe aceticaciditself has been decomposed in the operation; fer the carbonate of potash, which is in that case formed, is insoluble in alcohol. To spare trouble and expense, attempts have been madeto prepare acetate of potash with undistilled vinegar, and even with the residuum of the distillation of acetic acid; and they have been, to a certain degree, successful: but, as repeated fusion and crystallization are necessary to bring the salt to a certain 267 water, as much as is sufficient thoroughly to neutralize the: acid, The effervescence being finished, strain the liquor through paper, and, after evaporation, set it aside to crystallize. Sulphate of potash maybe also conveniently prepared from the residuum of the distillation of nitrous acid, by dissolving it ia warm water, and saturating it with carbonate of potash. Virriotatep Kart. (Kali Vitriolatum. L.) degree of purity, it does not appear that they were more cconomical. But if to acetate of potash, prepared with impure vi- Take of the salt which remains after the distillation of the nitrous acid, two pounds; Begar, weaddasuflicient quantity of sulphuric acid, by distillation we obtain an acetic acid of great strength, which forms a beautiful acetate of potash without fusion. Lastly, this salt may distilled water, two galldns : Burn out the superfluous acid with a strong fire in an open ves- be prepared by the decomposition of acetates; for example, of the acetate of lime by tartrate of potash. Acetate of potash has a sharp, somewhat pungent, taste. It is soluble at 60° in about its own weight of water. It is also soluble in alcohol. It is deliquescent. It is decomposed by the stronger acids; by a decoction of tamarinds; by the sulphates of soda and of magnesia; by muriate of ammonia; bythetartrate of soda and potash ; and by some metalline salts. Its acid is destroyed by a high temperature, sel; then boil it a little while in water; strain, and set the liquor aside to crystallize. This salt is very seldom prepared on purpose, as it may be obtained from the residuum of many other preparations, by simple solution and crystallization ; for so strong is the aflinity between sulphuric acid and potash, that they scarcely ever meet without combining to form this salt, All the sulphates, except that of baryta, are decomposed by potash and most ofits combinations ; and reciprocally, all the compounds of potash are decomposed by sulphuric acid and most of its combinations ; and in all these decompositions sulphate of potash is one ofthe proMEDICAL USE. ducts. Acetate of potash, however prepared, provided it be properly The greatest part of the sulphate of potash of commerce is made, is a medicine of great eflieacy, and may beso dosed and managed, as to prove either mildly cathartic, or powerfully diuretic: few of the saline deobstruents eqnal it in virtue. The dose is from half a scruple to a drachm or two. A simples0lution, however, of carbonate of potash in vinegar, without exsiccation, is perhaps not inferior, as a medicine, to the more expensive salt. Two drachms of the alkali, saturated with vie uegar, have produced, in hydropic cases, ten or twelvestools, and aplentiful discharge of uriue, without any inconvenience. obtained fromthe residuum of thedistillation of sulphate ofiron with nitrate of potash by lixiviating it, super-saturating the so. lution with carbonate of potash, filtering it boiling hot, and allowing it to crystallize. ‘The liquor remaining after the precipi. fe) f t ation of magnesia is also a solution of sulphate of potash. It is Sureuate or Portas, rormerty Virrionarep, Tartan. (Sulphas Potasse, olim Vartarum Vitriolatum. E.) Take, of sulphuric acid, diluted: with six times its weight of water, any quantity ; r> st sind waata Acs alates in Put it into a capaciou it vessel, and gradually drop into s glass also got in considerable quantities from the residuum remaining in the retort after the distillation of nitrous acid; andall the colleges have given directions for obtaining it in this way. This residuum generally contains an excess of acid,. which converts part of the sulphate into super-sulphate of potash. The London college expel the excess of acid by intense heat, and thus get the Whole of the sulphate ; but, at the same time, convert it into a very diflicultly soluble mass, while the Mdinburgh and. Dublin Colleges derive advantage from the excess ofacid, by simply sa~ with carbonate of potash. |