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Metallic Preparations. — Arsenic. part hi.

roasting ores of cobalt. Although prepared on a great scale,yet it is as pure as sublimation can make it, and therefore thisprocess is superfluous; and as it is also not devoid of risk tothe operator, it should be altogether rejected.

LIQUOR ARSENICALIS.« Lond. Arsenical Solution.

" Take of prepared oxide of arsenic rubbed to a very finepowder, subcarbonate of potash from tartar, each sixty-fourgrains ; distilled water, a pint. Boil them together in a glassvessel until the arsenic be entirely dissolved. Add to the so-lution when it is cold compound spirit of lavender, four fluiddrachms; and then as much distilled water as will make thewhole up to a pint."

Solutio Arsenicalis. Edin. Solution of Arsenic.

" Take of oxide of arsenic rubbed to very fine powder, verypure subcarbonate of potash, of each sixty-four grains ,• dis-tilled water fourteen ounces. Boil them together in a glassvessel until all the oxide be dissolved. Add to the solution,when it is cold, half an ounce of compound spirit of lavender,and as much distilled water as will make the whole up tosixteen ounces."

The white oxide of arsenic possesses properties in somerespect similar to those of an acid. It combines with alkalies,is soluble in water, and the solution reddens tincture of litmus:but it also combines with and neutralizes the acids; so that,while some ' regard it as an acid, others 3 consider it only as ahighly oxidized oxide. In the above process, by combinationwith the potash, its solubility is much increased, and a solutionobtained of an uniform strength, by which very minute dosescan be correctly and easily apportioned. It was introduced byDr. Fowler of Stafford, whose formula the London College hasadopted, altering only the proportions of the water and thespirit of lavender, to make up the pint of the solution.

dualities. — This solution, one fluid drachm of which con-tains half a grain of oxide of arsenic, has the odour, taste, andcolour of the compound spirit of lavender. It is decomposedby lime-water and hydrosulphuret of potash, and instantlyforms a copious precipitate when dropped into infusion or de-coction of cinchona bark; with which, therefore, it ought notto be conjoined in extemporaneous prescriptions.

Medical properties and uses. — The arsenical solution, as itis termed, is a powerful tonic, useful in all the cases in which

i This appellation is certainly very objectionable, aa it conveys an erroneous ideacf the preparation, even admitting that the term arsenic may be used to designate the■while oxide: it should have been Liquor Arsenialis Polassts, or perhaps more properly.Liquor alcalinus Oxuli Arsenici. /

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