92 
PREPARATION OP CALOMEL. 
The tube is heated to dull redness at that part nearest to the 
receiver, then the fire is extended by degrees along its whole 
length. An hour and a half or two hours is sufficient to 
complete the sublimation of twelve or fourteen pounds of 
calomel. 
When the operation is considered to be finished, the ap- 
paratus is unluted, and the calomel is washed with distilled 
water until the water ceases to be colored by sulphuretted 
hydrogen. The calomel is afterwards dried by a very gentle 
heat. 
Such is the very simple method of operating to which I 
have arrived, and I feel confident it is that which is kept 
secret by the manufacturers in England, for the calomel 
produced will bear comparison with the very best that is 
imported from that country. This is a triumph acquired to 
our commerce. 
I am now occupied in applying this process to the divi- 
sion of other volatile mineral substances, and have already 
effected its application to some. The operation presents 
difficulties in the cases of orpiment and cinnabar, arising 
from these substances requiring the contact of air at a high 
temperature. 
Pharm, Journ.,from Journal de Pharmacie. 
