1819.] Oxides and Salts of Mercury. 323 



from my former analysis of black oxide by only O04, and was 

 probably owing to my not having expelled the whole of the 

 water. 



47. The oxysulphate (40), when precipitated by potash, 

 afforded a yellow-coloured oxide, which agreed in its composi- 

 tion with that of red oxide prepared by calcination, except in 

 containing 0*25 of water. 



48. It has been conceivedby some that these precipitates are not 

 oxides, but subsalts. To ascertain how for this is true, I decom- 

 posed seme subsulphate of mercury (44) by means of potash. The 

 precipitate was repeatedly washed with distilled water, and was 

 afterwards boiled almost to dryness with muriatic acid, which 

 would separate any sulphuric acid that had adhered to the 

 oxide. It was then boiled with a little distilled water, and 

 filtered. In this liquor, muriate of barytes gave a scarcely per- 

 ceptible cloudiness. 



49. Some suboxysulphate was then decomposed by potash ; 

 the precipitate was repeatedly washed with distilled water, and 

 dissolved in as much muriatic acid as was barely sufficient. In 

 this solution, muriate of barytes gave no greater cloudiness than 

 in the former case. 



50. Hence, although these precipitates do retain a little of the 

 acid, the quantity is so extremely minute that analysis scarcely 

 detects it : and hence it is plain, that instead of subsalts, they 

 should be considered oxides, as pure as the generality of sub- 

 stances obtained by art. 



III. Combination of the Muriatic Acid with the Oxides of 



Mercury* 



Chemists have hitherto been acquainted with but two combi- 

 nations of muriatic acid and mercury; one with the black, and the 

 other with the red oxide. I have found that the muriates fall 

 within the general analogy of the mercurial salts, and that we 

 can form the subsalts of those already known. 



51. When calomel is 20 or 30 times boiled in different por- 

 tions of distilled water, it will be found to have become gray. If 

 the waters be evaporated down, they will afford indications of 

 muriatic acid. This is, therefore, submuriate of mercury -a 

 name which in the pharmacopoeias has been erroneously attri- 

 buted to the real muriate of mercury. It is also found when 

 calomel is boiled in muriatic arid (1175); when black oxide of 

 mercury is triturated in the cold with muriatic acid ot the same 

 specific gravity; or when calomel in a thin stratum is exposed 

 to the rays of the sun. The L <i mode of obtaining it is by cold 

 trituration, as above-mentioned i 



52. Although strong muriatic acid taktr, acid from calomel, 

 yet very dilute muriatic acid gives an additional dose to submu- 



• As to tbe new doctrine of chlorine, I here neither adopt nor reject it. I use 

 tlie old terms, being m.irc generally urnlcr-fi. >. 



x 2 



