HOW THE GAS IS MADE II 
and crystalizes when cold. It is easily soluble in 
water. Immediately after the room, tent, or other 
inclosure has been ventilated the desired length of time 
the contents of the jar should be emptied on a manure 
pile, in a hole prepared especially for that purpose, or 
under the tree close to the trunk. As the acid and 
potash left behind are both excellent fertilizers they 
should be saved by composting them either with 
manure or dirt. The residue consists of sulphate of 
potash, sulphuric acid, and water. The sulphuric acid 
will unite with lime in the soil, forming gypsum. 
Never pour the residue in an exposed place, where a 
person would be liable to step in it, or where a tent 
can be dragged through it. 
No dangerous deposit formed.—The question is 
often asked about the possibility of hydrocyanic acid 
gas forming a deposit upon any of the substances with 
which it might be brought in contact in its ordinary 
use asa fumigant, either in greenhouses or in buildings 
infested by indoorinsects. Dr. H. W. Wiley, chemist 
of the United States Department of Agriculture, 
states that there is no possibility whatever of such a 
contingency, unless the gas comes in contact with some 
alkaline body, such as soda or potash, with which it 
would formasalt. ‘Thesoluble cyanides are extremely 
poisonous, and if this gas were to act upon lye, or any 
similar alkaline body, a certain amount of cyanide 
would be produced. Jn a dry room, in the absence of 
alkaline bodies, there could not be any possible danger of a 
poisonous body being formed. 
