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Show ae =e ae Te _ ‘ ‘ ae ae pias ‘ e3 ea 268 PRICKLY SALTWORT. As the residuum of the distillation of nitrous acid may not always be at hand, the Edinburgh college also give a receipt for making this salt, by directly combining its constituents. It would have been more @conomical to have used asolution of sulphate of iron in place of sulphuric acid, by which means not only an equally pure sulphate of potash would have been pros cured at less expense, but also a very pure carbonateof iron. Sulphate of potash forms small, transparent, very hard cry. stals, generally aggregated in crusts, and permanent in the air, it has a bitter taste, is slowly soluble in water, requiring 16 parts at 60°, and 4 at 212°. It is not soluble in alcohol. It decrepitates when thrown on live coals, and melts in a red heat. {t consists of 45-2 acid, and 54-8 potash. It is decomposed by the barytic salts; by the nitrates and muriates of lime and of strontia ; by the tartrates partially ; and by the salts of mercury, silver, and lead. MEDICAL USE. Sulphate of potash, in small doses, as a scruple, or half a drachm, is an useful aperient; in larger ones, as four or five drachms, a mild cathartic, which does not pass off so hastily as the sulphate of soda, and seems to extend its action further. It isa charming medicine conjoined with rhubarb; thus scruple of the powder, a drachmof the tincture, with a scruple and a half of sulphurated kali, which quickens the action of the latter, mixed with six drachms of cinnamon and peppermint water, forms a mild aud pleasant opening draught. Sulphas Potasse cum Sulphure, olim Sal Polychrestus. E. Take of nitrate of potash in powder, sublimed sulphur, of each equal parts : Mingle them well together, and inject the mixture, by little and litle at a time, into a red-hot crucible: the deflagration being PRICKLY SALTWORT. sulphate of potash. 269 It is crystallizable, and, by exposure tothe air, gradually attracts oxygen, andis conve rted into sulphate of potash. ‘¢In some experiments,” says the learned and ince. nious Dr. Duncan, ‘ which I made to deter mine the otein which the sulphur existed in this salt, carefu lly prepared, it seemed to be sulphuric acid; for it neither gave out a sulphureous smell on the addition of sulphu ric acid, nor was a solution of it precipitated by acids. Inits medical effects and exhibition it agrees with sulphate of potash. Oxymurratic AuKkatine Water. (Aqua Alcalina Oxy. muriatica. D.) Take of dried muriate of soda, two pound s; manganese, in powder, one pound ; water, —— sulphuric acid, of each two pound s; Put into a matrass the muriate of soda and manganese, mixed. and pour on the water ; then, by means of a proper apparatus add gradually, and at different times, the sulphuricacid, and let the gas evolved pass througha liquor consi sting of Carbonate of kali, four ounces; . Water, twenty-nine ounces, by measure. Towards the end of the operation heat the matrass moderately. The specific gravity of this liquor is 1087. " This is a solution of the oxymuriate of potash ; forthe car. bonate of potash in the receiveris decomposed by the oxymu- atic gas disengaged in the matrass bythe action of the sulphuric acid on the oxide of manganese and muriate of soda. A aieed sulphate of soda and manganese remai ns in the retort, while the oxyge n and the muriatic acid, disengaged, unite in their nasce nt a and form oxymuriatic acid, which escapes in the form of over, let the salt cool, after which it is to be put upin a glass vessel well stopped. In this process the nitric acid of the nitrate of potash is decomposed by the sulphur, which is in part acidified. But the quantity of oxygen contained in the nitric acid is not always sufficient to acidify the whole sulphur employed; therefore, part of it remains in the state of sulphureots acid, which is probably chemically combined with part of the potash in the state of sulphite; for the whole saline mass formed is more soluble in water than MEDICAL USE. Siha ohanne elt rarely, o if at all, ‘ a a used‘a . 4 It was w; also ] rec somi ommmeend a ed asian ,oxy : gen seis a ” ns yp uss SCUETY, and other dise ases supposed to Paha Esai ney of oxygen in the system. It was given in Bh ve to fitter grains, three times a day ; and it and impartial trial. |