constitution of the prussic and other acids, &c. 223 
D. I had next to ascertain how much red oxide. of mercury 
was represented by the 37.2 grains of black sulphuret obtained 
in Experiment B, and by the 9.3 grains of the same substance 
obtained in Experiment C. In order to effect this, I made the 
following experiment: 25 grains of corrosive sublimate were 
dissolved in water, and decomposed by hydro-sulphuret of 
potash; the black sulphuret thus formed, weighed 21.5 grains, 
which, therefore, represents 19.94, grains of red oxide of 
mercury, that being the quantity contained in 25 grains of 
corrosive sublimate. 
Then as 21.5 : 19.94 : '• 37* 2 : 34-48 the quantity of red oxide 
in 40 prussiate of mercury, 
And as 21.5 ; 19.94 : : 9-3 : 8-62 the quantity of ditto in 10 of 
ditto, 
100 grains of prussiate of mercury are therefore composed of 
Prussic acid, Experiment C. - - 13.8 
Red oxidfc of mercury, Experiment B. C, and D. 86.2 
100.0 
Analysis of prussic acid. 
Being very desirous of accomplishing the analysis of this 
acid if possible, I considered very attentively the nature of 
the difficulties to be surmounted in order to effect it. The 
principal ones appeared to me to be the following. 
1st. That of always ascertaining with precision, the quan- 
tity which is the subject of analysis. 
gd. That of effecting its combustion with oxygen in such 
a manner, that while, on the one hand, the whole of its carbon 
and hydrogen should be oxygenated, so on the other, that 
none of its azote should undergo this process. 
