1819.] Oxides and Salts of Mercury. 325 



merely presenting distilled vinegar to the black oxide, we must 

 infer this black oxide to be also the basis of calomel. Another 

 reason is, that if a solution of black oxide in boiling distilled 

 vinegar be mixed with common salt, calomel immediately forms. 

 The analysis of this oxide has been already detailed. 



57. The oxymuriate of mercury evidently contains the per- 

 oxide ; for the fixed alkalies separate it unaltered, and the 

 common red oxide, by simple solution in muriatic acid, affords 

 oxymuriate. It appeared unnecessary, therefore, to ascertain its 

 analysis by another trial. 



58. If a solution of corrosive sublimate be exposed to the 

 action of light, I have found that some calomel is formed, and, 

 therefore, the oxide afforded by potash will not be the pure red 

 oxide. 



As to the oxides contained in the submuriate and suboxymu- 

 riate, there can be no doubt of their constitution. 



59. The only remaining question on this part of the subject is, 

 whether or not the precipitates obtained from the muriates 

 of the two oxides be pure oxides or contain a portion of acid 

 united to them. A solution of corrosive sublimate was precipi- 

 tated with pure potash, the precipitate was well washed with 

 distilled water, and dissolved in boiling dilute nitric acid very 

 pure. To this solution was added solution of nitrate of silver ; 

 but the transparency was not in the least impaired, even when 

 cold. 



60. Calomel being decomposed by potash in the same man- 

 ner, and its oxide dissolved in boiling dilute nitric acid, there 

 was no change whatever produced by nitrate of silver. Hence 

 these precipitates are pure oxides. 



IV. Combination of the Acetic Acid with the Oxides of Mercury. 



61. If distilled vinegar be boiled on black oxide of mercury, 

 a simple solution takes place, and the acetate is deposited 

 abundantly, as the fluid cools ; or if distilled vinegar be boiled 

 in nitrate of mercury, it is decomposed, and acetate forms in 

 abundance. 



62. If these crystals be separated, and triturated with a large 

 quantity of water, they become yellow ; and if the yellow crys- 

 tals be boiled in water, they change to a blue grey powder. The 

 same powder may be formed at once, by triturating black oxide 

 with distilled vinegar. It is also slowly formed, when acetate of 

 mercury is exposed to strong light. This salt, which has not 

 hitherto been recognized, is subacetate of mercury. 



63. When this salt is boiled in water, crystals of acetate are 

 formed as the solution cools ; for the subsalt is still further 

 deprived of acid, and this, dissolving a portion of the subsalt, 

 forma a quantity of the neutral salt. The yellow crystals above- 

 mentioned are the subsalt, nearer to the point of saturation thau 

 the grey. 



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