REMARKS ON SOME OF THE MERCURIAL COMPOUNDS. 53 
ing it to be protochloride of mercury; these experiments 
were conducted in a manner not intended to ascertain the 
quantity or per centage of oxide of mercury, but to prove its 
presence, which, to my own mind, they most satisfactorily 
have done. Finally, as to the cause of the activity of this 
preparation, no one who has any knowledge of even the ele- 
mentary principles of chemistry, can ascribe it to any other 
than the presence of the protoxide of mercury; and to uphold 
any other belief, to say the least of it, betrays ignorance of 
the properties of the metal and its compounds. 
Among the varieties of this article met with in this coun- 
try, all or nearly all are prepared in England, and should be 
carefully examined before being used. Some manufacturers, 
in order to brighten the color of the conserve of roses, used 
in its preparation, add to it a small quantity of sulphuric acid, 
which remaining in contact with the mercury, (or its oxide 
rather) forms a sulphate of mercury formerly called Turpeth 
Mineral, violently irritative in its action, which of course it 
imparts to the mass with which it is incorporated; of this seve- 
ral examples have been recently observed, and the pernicious 
effects clearly traced to this cause. 
One of the best preparations which has been seen for some 
time past occurs in pound rolls, wrapped in tin foil and brown 
paper, with a plain label of " Pil. Hydrargyri" on the out- 
side, and presumed to be manufactured by Davy Macmurdo 
& Co., London. 
HYDRARGYRUM CUM CRETA, 
Though generally considered as less important and less fre- 
quently used than Pil. Hydrargyri, still forms a component 
of the physician's prescription. It is prepared by rubbing to- 
gether three parts of mercury, and five of prepared carbonate 
of lime, until all appearances of globules have ceased to be vi- 
sible, even with the aid of a lens. 
Its action has been attempted to be explained, on the sup- 
position that it is only mercury finely divided, but when de- 
