ABSORPTION OP SALINE SUBSTANCES BY CHARCOAL. 141 
cipally the action of charcoal upon the acetate and nitrate of 
lead, arsenious acid, nitrate of silver, sulphate of copper and 
ammonical sulphate of copper, hydrate of lead dissolved in pot- 
ash, solution of iodine, Labarraque's solution, chloride of lime, 
and liquid chlorine. He states that, however large the quan- 
tity of charcoal employed, he was never able to precipitate 
arsenious acid and sulphate of copper. The contrary was the 
case with all the other salts. M. Lassaigne found that char- 
coal, placed in contact with iodide of starch and with a solu- 
tion of iodine, removes the iodine from the liquid. M. Dupas- 
quier observed that vegetable charcoal absorbs quickly and 
even in considerable quantity the alkaline sulphurets. I have 
repeated this experiment comparatively with vegetable and 
animal charcoal, and have found that it requires nearly three 
and a half times more of the former than of the latter to ob- 
tain the same result. 
In 1845, M. Chevalier published in the 'Annales d'Hygiene,' 
that the acetate and nitrate of lead in solution in water, wine, 
or vinegar, might be removed from these liquids by means of 
charcoal, with or without the assistance of heat. He was led 
to believe that this new property would furnish a ready and 
easy means of removing from some orange-flower waters,which 
had been kept in badly-tinned vessels, the lead salts they might 
have dissolved, without depriving the waters of their odor. 
The experiments which he made on this subject perfectly con- 
firmed his suppositions. M. Chevalier also observes very cor- 
rectly, that this property of charcoal of combining with the 
metallic oxides may frequently have been the source of error in 
chemico-legal inquiries. 
This question has also been examined by M. Giradin, who 
found that not only the majority of salts, but even most min- 
eral substances, were removed from solution by animal charcoal ; 
a property which he turned to excellent account in depriving 
water in newly constructed reservoirs of a disagreeable flavor, 
which renders its use for a long time impossible, owing to the 
lime which it removes from the walls. 
