ANNALS 



OF 



PHILOSOPHY. 



NOVEMBER, 1819. 



Article I. 

 On the Oxides and Salts of Mercury. By Mr. Donovan, 



{Concluded from p. 251.) 



II. Combination of the Sulphuric Acid with the Oxides of 



Mercury. 



39. I find that when strong sulphuric acid ha any quantity is 

 heated on mercury so gently that the metal barely effervesces, a 

 white salt is speedily deposited, which is the real sulphate of 

 mercury, containing no other than the black oxide. It dissolves 

 very sparingly in sulphuric acid, whether hot or cold, and is 

 decomposed by water. 



40. When this sulphate is boiled in sulphuric acid, the acid is 

 decomposed, the oxide takes up an additional portion of oxygen, 

 and forms a white, crystalline, permanent salt, which contains no 

 other than the red oxide, and is hence oxysulphate. 



41. When sulphuric acid is violently boiled on any quantity of 

 mercury, the metal is primarily brought to the state of black 

 oxide, which may be detected in it ; but the sulphate at this 

 temperature, further decomposes the acid and forms oxysulphate. 

 If the quantities be two of mercury to three of the strongest acid, 

 the whole becomes oxysulphate ; but if the ratio of acid be less, 

 there will be an admixture of sulphate. 



42. Berthollet forms the sulphate by boiling sulphuric acid 

 diluted with its weight of water on mercury. In this case great 

 caution is required ; for the acid does not act until it becomes 

 more concentrated by boiling ; and during the progress of solu- 



Voi.. XIV. N° V. X 



