l Calomel, &c. , [Book VI. 



and of a more filvery appearance. The ingredients, 

 howef er, are not fufficiently mixed by the firft fub- 

 limation ; they muft be rubbed together again and fub- 

 limed; and thefe prqcefles muft be repeated at leaft 

 three times. 



The converfion of the .corrofive fublimate into the 

 rniider fubftancc, Calomel, may be explained on the 

 following principles : In the corrolive fublimate,, the 

 muriatic acid is /bund to be combined with a very 

 large quarry f oxygen, which renders it extremely 

 active ^y t * ne Edition of mercury, a quantity of 

 AiS ftiperftuous oxygen is abftradbed, for the calcina- 

 tion of the additional metal ; and the whole mafs, 

 therefore, contains the acid not only in a milder (late, 

 but the fame quantity of acid is diffufed through a 

 larger mafs of the metal. 



Ponderous earth, magnefia, and lime, decompofe 

 the corrofive fublimate, and precipitate a mercurial 

 calx. The phagedenic water, made ufe of as a cor- 

 rofive by furgeons, is made by throwing half a drachm 

 of corrofive fublimate, in powder, into a pound of 

 Jime water ; a yellow precipitate is then formed, which 

 renders the liquor turbid. 



Acids and neutral alkaline falts produce no change 

 on corrofive fublimate, but it contracts an intimate 

 union with fal ammoniac without decompofition. The 

 fal ammoniac renders corrofive fublimate very folublc. 

 The calx hydrargyri alba of the London Pharma- 

 copeia is obtained from this combination. A quan- 

 tity of fal ammoniac is diflblved in diftilled water; 

 an equal \veight of corrofive fublimate is then added ; 

 when this is diflblved, fixed vegetable alkali is added, 

 which produces a white precipitate. In this operation 

 ihe fixed alkali difengages the volatile alkali of the fal 

 ammoniac, which precipitates the mercury in the form 

 * of 



