446 



HOUSEHOLD INSECTS 



elsewhere. Such strips will stick closely for several hours 

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

 Careful attention should be given to the matter of tighten- 

 ing the room. The gas will so quickly dissipate itself 

 through holes and cracks, if these are left open, that its 

 effectiveness will be greatly lessened, if not entirely lost. 

 While the room is being made tight, some one should 

 measure out the ingredients according to the formula 

 already given. The water should be measured and 



poured first into a stone 

 jar holding at least 

 two gallons. The jar 

 should be placed in 

 the middle of the room 

 with an old rug or 

 several newspapers un- 

 der it to protect the 

 floor. If the generat- 

 ing jar is too small, the 

 liquid may boil over 

 and injure the floors 

 and rugs. Careful at- 

 tention should be paid to protecting polished floors, valu- 

 able rugs, and carpets. The latter had better be removed 

 entirely. If the room is a large one, a larger jar, or two 

 or more small ones, will be necessary to hold the requisite 

 amount of cyanide, acid, and water in order to prevent 

 spattering. 



The required amount of sulfuric acid should then be 

 poured rather slowly into the water. This procedure 

 must never be reversed, that is, the acid must never be 

 poured into the jar first. The cyanide should be weighed 



Fig. 152. — A room " strung " for 

 fumigation." 



