445 
PRODUCTION OF SULPHURIC ACID FROM GYPSUM. 
Hr. Kohsel has devised a method of obtaining sulphuric 
acid, which consists in converting gypsum into sulphide of 
calcium by igniting it with carbon in cylinders, then ex- 
posing the sulphide mixed with water, to the action of 
carbonic acid gas at a moderate temperature, burning the 
sulphuretted hydrogen thus produced, and afterwards treat- 
ing the sulphurous acid and water vapour in the ordinary 
way in lead chambers. The carbonic acid gas generated in 
the first stage of the process is used for decomposing the 
sulphide of calcium of a subsequent charge, and the waste 
heat of the igniting furnace is made available for producing 
the requisite temperature for this decomposition. — Pharma - 
ceiitical Journal, 
COLLODION AS AN ESCHAROTIC. 
Dr. Macke states, in the Medicinische Cent. Zeitung , that 
he has used with advantage an escharotic composed of one 
ounce of collodion to one drachm of corrosive sublimate. He 
has used it principally in naevi, and small excrescences which 
patients wished to get rid of without the use of the knife. 
It is applied with a camePs-hair pencil, dries rapidly, and 
cannot be rubbed off easily. Applications of cold water may 
be made in cases where the inflammation runs high, without 
interfering with the action of the caustic. The eschar is 
thin, and falls off after three or mostly six days ; pain is 
very slight, and the author has not found that any absorption 
of the bichloride takes place . — The Lancet. 
THE BEST WAY OF WITNESSING THE CIRCULATION OF 
THE BLOOD. 
Dr. Wagner, of Gottingen, advises, for this purpose, the 
use of animals narcotized by chloroform, whose mesenteric 
capillary vessels only allow of the passage of one row of 
blood-globules. The rapidity of motion can, under such 
circumstances, be easily ascertained. — The Lancet, 
