METALLIC COMPOUNDS. 
consequently should not contain mercury, was a superoxidutn 
stibicum. I endeavoured to decompose it in a small retort to 
disengage the excess of oxigen, but to my great surprize I 
found mercury condensed in the neck of the retort, while the 
colour of the powder became changed to yellow. I endeavour- 
ed, therefore, to decompose this combination, by means of con- 
centrated muriatic acid, with which I kept it in digestion. The 
acid in fact dissolved a small quantity, but, on diluting the 
solution with water, the greatest part was deposited. The 
precipitate thus formed was greenish grey, and appeared to con- 
tain less oxide of mercury than before. The portion not dis- 
solved by the muriatic acid, still preserved its colour and all its 
properties. I separated the acid from it, and washed it very 
well, and afterwards dried it by heat approaching to ignition. 
200 parts of this dried combination exposed to a moderate heat 
in a glass retort exactly weighed, until nothing remained in the 
retort, but the yellow stibic acid lost by this evaporation 31*5 p. 
in weight, of which I found 29 p. of metallic mercury in the 
neck of the retort. The receiver contained oxigen gas ; and 
therefore, the loss of 2'5 p. must be attributed to this gas, and 
corresponds very nearly to the oxigen required to convert these 
2 9 parts of mercury into red oxide (the exact quantity needful 
being 2’3 p.) The stibic acid which remained in the retort, lost 
in a still stronger heat 6*5 per cent, and became converted into 
stibious acid. This experiment appears, therefore, to prove, that 
olive coloured substance contains nothing but the stibic acid, 
and the red oxide of mercury ; and it appears that the stibiate 
of mercury had undergone, at the moment of its formation, the 
same change as the other metallic stibiates I have mentioned do 
by ignition. 
I 
(To he continued.) 
Extract 
