CHAPTER II 
HOW THE GAS IS MADE 
HE chemicals used for generating hydrocyanic 
acid gas are (1) fused cyanide of potassium 
(KCN), (2) sulphuric acid (H,SO,), and 
(3) water (H,O). The cyanide should be 
guaranteed 98-99 per cent., which is practically chem- 
ically pure. There is upon the market in some places 
an old brand of cyanide of about 58-60 per cent. 
purity. This should be avoided. 
The best grade of commercial sulphuric acid, with 
a specific gravity of at least 1.83, should be used. A 
grade known as chamber acid used ordinarily in the 
manufacture of fertilizers will not do, and under no 
circumstances should it be employed. Water from any 
source will suffice, the only requisite being that it 
should be clean. 
In combining the chemicals (1), measure the acid in 
the glass beaker marked ounces on the side, and pour 
it in an earthenware crock, wooden bucket, tub, or 
pickle jar; (2), measure the water in the same beaker 
and pour it on the acid; (3), drop in the cyanide, bag 
and all, if wrapped in paper, close the door or drop the 
tent quickly, and leave desired length of time. 
Aftion of the chemicals.—When the water is poured 
into the jar upon the acid, a slight evolution of steam 
arises, which is not dangerous. As soon as the cyanide 
is dropped in the acid and water there is a bubbling 
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