294 Facts towards the 



There remained a black powder not acted upon by strong solution 

 of potassa, nor by nitric, nor muriatic acid. It was collected upon 

 a filter, thoroughly edulcorated, and dried in a very moderate heat, 

 not at any time exceeding 212° ; it was then of a very dark violet 

 hue; when heated in a glass tube it sublimed without any evolution 

 of mercury, and became perfect cinnabar. It appears, therefore, 

 that Ethiops-mineral is far from being soluble without decomposi- 

 tion in alcaline menstrua ; on the contrary, solution of potassa 

 merely abstracts its excess of sulphur, furnishing a liquid sulphu- 

 retted hydrosulphuret of potassa, from which the acids throw down 

 sulphur, but which affords no traces of mercury. When, however, 

 moist bisulphuret of mercury, as it is left by the alcaline solution, is 

 boiled in a strong solution of hydrosulphuret of potassa, a minute 

 quantity of it appears to be taken up. 



There are some discrepancies in the chemical history of the bi- 

 sulphuret of mercury or cinnabar, as given in the above quoted 

 works, which the following facts may perhaps tend to clear up. 



Cinnabar is not altered (except slightly as to colour, which is 

 somewhat brightened whilst it is moist) by long-continued boiling 

 in nitric acid ; nor is it affected by muriatic acid under similar 

 circumstances. Nitro-muriatic acid instantly attacks it even in the 

 cold, and by boiling converts it into a persulphate of mercury. If the 

 sulphuric acid be precipitated by muriate of baryta, it is found that 

 eighty parts are obtained from 232 of cinnabar, indicating the 

 existence of two proportionals of sulphur to one of mercury, as 

 above stated *. Sulphuric acid is partially decomposed when 

 boiled upon cinnabar ; sulphurous acid gas is given out, and upon 

 boiling down to dryness a white sulphate of mercury is ultimately 

 obtained. The non-action of nitric acid upon cinnabar, considering 



* In this analysis of cinnabar it was found that 232 grains of cinnabar, after 

 having been acidified b)' nitromuriatic acid, required exactly 248 grains 

 of crj'stallized muriate of baryta for the precipitation of 236 grains of sulphate 

 of baryta. The correctness, therefore, of Mr. Phillips's equivalent for crystal- 

 lized tuuriate of baryta may be considered as established, viz., that it consists 

 iof 1 proportional of dry muriate (chloride of barium) = 106 + 2 proportionals 

 of water (9 x 2= 18) = 124. 



