58 
ON KERMES MINERAL. 
oxide. The kermes obtained by fusion contains, therefore, ox- 
ide of antimony, and the oxide only, and not antimonic acid, 
for by ebullition in tartar, crystals of tartar emetic may be ob- 
tained. 
I had supposed, depending upon the authority of MM. Gaj r - 
Lussac and Liebig, that the quantity of oxide of antimony in 
kermes, obtained by fusion, was very considerable. But 1 
have long since changed this opinion, as I have found that this 
quantity varies very considerably according to the different 
modes of obtaining it, and bears no relation in quantity to the 
sulphuret of antimony. Microscopic examinations have con- 
firmed this opinion, for kermes has the appearance of a mixed 
mass of red granules and crystals, the latter being in very va- 
riable quantity. We may even by this mode of preparation 
obtain a kermes which contains very little oxide, and which, 
after fusion, will yield, when pulverised in an atmosphere of 
carbonic acid, a powder almost black. 
The principal cause of the presence of this oxide in kermes 
is, that by fusion with an alkaline carbonate, the sulphuret of 
antimony is completely decomposed, while, by boiling in a so- 
lution of the same, the greater part escapes alteration. By fu- 
sion there is formed oxide of antimony, and a metallic alka- 
line sulphuret which dissolves the sulphuret of antimony. On 
boiling the fused mass in water and cooling the filtered liquor, 
kermes mixed with oxide of antimony is deposited, this latter 
precipitating, because the undecomposed alkaline carbonate 
does not bear a sufficient relative proportion to the decom- 
posed sulphuret of antimony. 
This explanation of the reactions taking place in this pro- 
duct does not appear wholly exact, on account of the separa- 
tion of metallic antimony, or rather there should be another 
process by which this separation may be explained. 
If we concentrate by evaporation the liquor from which the 
kermes has been deposited, this liquor on cooling will depo- 
sit a considerable quantity of large crystals of a well known 
salt of sulphur, consisting (when carbonate of soda is used) of 
sulphuret of sodium and sulphuret of antimony, with a maxi- 
