The Proportions of Ingredients 319 



THE PROPORTIONS OF INGREDIENTS 



Experiments and experience have shown that the potassium 

 cyanid should be ninety-eight per cent pure in order to give satis- 

 factory results. The purchaser should insist on the cyanid being of 

 at least that purity, and it should be procurable at not more than 

 forty cents per pound. The crude form of sulfuric acid may be used. 

 It is a thickish, brown liquid and should not cost more than four or 

 five cents a pound. If a room is made tight, one ounce of cyanid for 

 every one hundred cubic feet of space has been shown to be sufficient. 

 It is combined with the acid and water in the following proportions : 



Potassium cyanid i ounce 



Commercial sulfuric acid i fluid ounce 



Water 3 fluid ounces 



A SINGLE ROOM AS AN EXAMPLE 



Suppose a room to be 12 by 15 by 8 feet. It will contain 

 12x15x8, or 1440 cubic feet. For convenience the writer always 

 works on the basis of complete hundreds; in this case he would 

 work on the basis of 1500 cubic feet, and thus be sure to have enough. 

 The foregoing room, then, would require 15 ounces of cyanid, 15 

 ounces of sulfuric acid, and 45 ounces of water. The room should 

 be made as tight as possible by stopping all the larger openings, 

 such as fireplaces and chimney flues, with old rags or blankets. 

 Cracks about windows or in other places should be sealed with narrow 

 strips of newspaper well soaked in water. Strips of newspaper two 

 or three inches wide that have been thoroughly soaked in water may 

 be applied quickly and effectively over the cracks around the window 

 sash and elsewhere. Such strips will stick closely for several hours 

 and may be easily removed at the conclusion of the work. 



While the room is being made tight, the ingredients should be 

 measured according to the formula already given. The water should 

 be measured and poured first into a stone jar for holding at least two 

 gallons. The jar should be placed in the middle of the room, with 

 an old rug or several newspapers under it in order to protect the floor. 



The required amount of sulfuric acid should then be poured 

 rather slowly into the water. This process must never be reversed; 

 that is, the acid must never be poured into the jar first. The cyanid 

 should be weighed and put into a paper bag beside the jar. All hats, 

 coats, or other articles that will be needed before the work is over 



