of some Oxides of Mercury. 133 



mercury does not arise from a semi-vitrification, as M. Van 

 Mons asserts, M. Paysse made a solution of mercury in 

 nitric acid mixed with some hundredths of muriatic acid. 

 Having evaporated the solution to dryness, he treated this 

 matter with the same care and caution as the former ; and 

 when the operation was finished the mercurial oxide exhi- 

 bited a red aspect, sufficiently beautiful in some parts and 

 dull in others, but without any appearance of brilliancy or 

 crystallization. This mass was pulverized, and again in- 

 troduced into another glass vessel, into the bottom of which 

 he took the precaution of pouring a small quantity of nitric 

 acid, that the mercurial powder might be slightly impreg- 

 nated. He then proceeded as before, exposing the vessel 

 to a gentle and graduated heat. But, notwithstanding all 

 the precautions he observed during the operation, the oxide 

 which was the result of them had passed to red without 

 exhibiting the least vestige of crystallization or brilliancy. 

 This experiment was repeated three times, but with lio 

 better success. It is evident, however, that if the red oxide 

 of mercury is indebted for its brilliancy only to the semi- 

 vitrified state it experiences \vhen heated, there is no reason 

 why this matter should not be constantly in the same state 

 every time it is prepared, since nothing is necessary, ac- 

 cording to Van Mons, but to apply to it a violent heat be- 

 tween two crucibles luted together.' 



In preparing crystallized red oxide of mercui-y, M. Paysse 

 made observations which gave him reason to suspect that 

 •the brilliant state of this substance is ovi'ing rather to the 

 constant degree of the oxygenation in which the mercury 

 is, than to any other cause," and that the presence of the 

 muriatic acid in the nitric acid is an obstacle to the forma- 

 tion of that brilliant state by the new combinations to which 

 k gives birth during the operation. What he supposed is 

 now become certainty, as the following experiments will 

 show. 



He took a hundred parts of red oxide of mercurv, brilliant, 

 and prepared by nitric acid mixed with muriatic acid ; and, 

 having introduced them into a loug-ncckcd matrass fur- 

 nished with a bent glass tube con)mimicating with a pneu- 

 matic apparatus, they were gradually healed till the bottom 

 of the vessel became red. He suffered to escape the whole 

 of the atmosphericair contained in the apparatus, that he 

 might obtain, free from mixture, the oxygen gas furnished 

 by the oxide. Having exposed the matrass to heat for a 

 f'un'icient time, axid waited for the complete reduction of 

 I 3 the 



