358 Mr. Porrett on Sulphuretted Chyazic Acid. [May, 
when cyanogen and sulphuretted hydrogen are mixed together ; 
it also contains azote and sulphuret of carbon, the latter readily 
distinguishable by its peculiar smell, and sometimes a minute 
quantity of sulphuretted chyazic acid comes over with it unal- 
tered. From 10 gr. of sulphuretted chyazate of copper, I 
obtained about two cubic inches of this mixture of gas and 
vapour over mercury ; but this diminished considerably in bulk 
as the vapour condensed, the surface of the mercury at the same 
time becoming tarnished ; and there remained after the action 
of an alkaline solution only about half a cubic inch of azote. 
The same quantity of sulphuretted chyazate, when previously 
mixed with half its weight of copper (in that state of minute 
division in which it is precipitated from its solutions by iron) 
gave, on the application of heat, about three cubic inches of 
permanent gas, which was cyanogen. 
2. The sulphuret left behind containing the metal in the 
metallic state, is nothing more than what should occur consi- 
dering that the oxygen in the protoxide is only in the proportion 
necessary to form water with the hydrogen of the acid; it there- 
fore follows, as I said before, that when the compound is 
decomposed by heat, water must be formed, and the metal 
reduced ; but it does not follow that the metal was in this state 
before that decomposition takes place. 
3. The little solubility of sulphuretted chyazate of copper in 
muriatic acid will, I apprehend, be thought a very inadequate 
roof that it contains the copper in the state of metal, when it 
is considered that oxalate of copper has also very little solubility 
in this menstruum, and yet it contains the copper in the state of 
peroxide ; and that, on the other hand, cyanuret of mercury,: 
which contains the metal in the metallic state, is very soluble 
therein. 
4, With respect to the argument that the carbon, hydrogen, 
&c. of the sulphuretted chyazic acid must undoubtedly reduce 
the easily reducible oxides, I conceive it will be sufficient answer 
to state that, if there were any truth in this remark, the acetates 
of silver, mercury, and copper, with a variety of similar salts, 
could have no existence. 
5. With regard to the brown copper colour which a mixture 
of acetate of copper with alcohol momentarily assumes when 
sulphuretted chyazate of potash is added to it, I can assert that 
the mixture becomes indeed brown, but presents no metallic 
appearance ; the colour is exactly similar to that of protomuriate 
of copper when it contains a httle permuriate; it, therefore, 
merely indicates. the presence of protoxide in the solution, but 
not that of metallic copper. 
Having thus shown that no grounds exist for considering 
sulphuretted chyazate of copper as an anthrazothionhydrate, I 
shall now show its real composition. 
In an experiment detailed in my paper, on the nature of the 
