HYDROCYANIC-ACID GAS AGAINST HOUSEHOLD INSECTS. 



The cubic contents of each room on each floor should be carefully 

 computed and a tabular statement, such as that given below, pre- 

 pared, designating for each floor and the different rooms the capacity 

 and the amount of water, acid, and cyanid needed. 



Tabic desiffnativff rooms, capacity, and amounts of chemicals. 



1 The charges for these rooms should be halved and set off in two vessels. 



The house is prepared for treatment by seeing that all the win- 

 dows are closed and calked, if of loose construction, with Avet paper 

 or cotton batting tucked tightly into the crevices. Gummed paper 

 strips are obtainable for this purpose, which may be pasted over the 

 crevices in the doors and windows, making the room practically 

 gas-tight. As the building must be aired by opening the windows 

 from the outside, those selected to be opened should be examined to 

 see that they pull down easily, and if too high to be reached from the 

 ground should be provided with strong cords reaching to the ground 

 that they ma}'- be easily opened from below. They should be opened 

 before closing for the last time, in order to test the strength of the 

 cord and should not be pasted up or calked. The fireplace flues in 

 the different rooms .should be stuffed with paper and the registers 

 closed. Carpets and rugs, where possible, should be cleared away 

 from the floor to prevent their being burned should the acid spatter 

 or boil over. 



For generators, stoneware or crockery jars having a capacity of 4 

 gallons are preferable and may be used with a charge of up to 3 

 pounds of cyanid. One of these vessels should be placed in each 

 room, with the exception of large rooms requiring a charge of more 

 than 3 pounds of cyanid, when the charge may be divided. One 

 vessel will suffice for each 3,000 or 4,000 cubic feet, preferably the 

 former amount. Under each of these vessels a rather thick carpeting 

 of old newspapers should be placed, or a larger vessel, and care must 

 be exercised to see that none of the vessels is cracked, on account of 



