PREPARATION OF ENGLISH CALOMEL. 
93 
ART. XX.— ON THE PREPARATION OF ENGLISH 
CALOMEL. 
BY M. CALVERT. 
The importance of being able to manufacture, in France, 
a calomel as good and as cheap as that which is imported 
from England, renders it a matter of interest to know the 
exact process adopted by the London manufacturers. It 
must be observed, however, that the following details are 
merely given as a supplement to the very ingenious paper 
on the preparation of calomel, by M. Soubeiran. This 
Chemist has in fact discovered the basis of the English pro- 
cesses method of operating differing only in the nature of 
the apparatus employed. The material principle is the 
same in both cases, namely, the employment of a chamber 
into which the vapour of the calomel is conducted, suffi- 
ciently large for the air contained in it to hold the particles 
of calomel in suspension during the condensation of the 
vapour, and thus to prevent its crystallization. 
The apparatus employed in England consists of an iron 
cylinder about thirty inches long and twelve inches diame- 
ter, closed at one end by a kind of door in the same way as 
the cylinders employed in the manufacture of hydrochloric 
acid. It is at this end that the materials used in making 
the calomel are introduced. The other end of the cylinder 
has a neck or contraction, six inches long and six inches in 
diameter. This neck is made large, so that it may not get 
stopped up by the condensation of the calomel. The neck 
of the cylinder penetrates the side of a bricked chamber, 
lined on the inside with flag-stones. This chamber is about 
six feet six inches high, and four feet six inches wide; the 
bottom is a little sloped, and in one of the sides is a door 
vol. ix. — NO. II. 9 
