CARBON DISULPHID AS AN INSECTTCTDE. 13 



the strongest action of the vapor. With this in view, materials 

 should be removed from shelves and spread out on the floor. If there 

 are serious objections to allowing the liquid to touch the materials 

 to be treated, it will be necessary to provide a large number of shal- 

 low tin pans or plates. The larger these are the better. They should 

 be placed as high in the room as can be done Avithout delaying the 

 application unduly, and care should be taken to see that they are 

 level, although ordinarily no harm will be done if some of the liquid 

 is spilled. No time can be lost in making such adjustments after the 

 application is begun. To reach places which are not accessible by the 

 pan method, it may be possible to use cotton waste or other absorbent 

 material, saturating it with the disulphid and throwing it or hang- 

 ing it where needed. If the liquid has been purchased in bulk it may 

 be necessary to have several convenient smaller receptacles into which 

 it may be poured so that it can be handled conveniently and rapidly. 



MAKING THE EXPOSURE. 



As many men should assist in making the exposure as can work 

 to advantage, for the work must be done rapidly. Before the cans 

 or drums are opened every man should receive full instructions as to 

 his division of the work, and cautioned as to the dangers from fii-e, 

 dizziness, etc. If more than one floor is to be treated, the men 

 should begin at the bottom and work upward on account of the rapid 

 settling of the gas. Every door and window should be closed tightl}^ 

 except that left for escape of the workers. All should begin at the 

 same time, pouring the predetermined amount into each receptacle, 

 and then get out into the open air as quickly as possible. The exit 

 door should then be closed, with paper pasted around it to make it 

 tight, and it should be left closed for 12 hours or longer. The best 

 plan usually is to make the treatment on Saturday afternoon before 

 dark, or on Sunday forenoon, and allow the building to remain locked 

 until early Monday morning. Owners of adjoining premises should 

 be advised regarding the nature of the work, and a watchman may be 

 needed in some cases during the period of treatment. 



VENTILATION. 



As a matter of fact, most, if not all, of the killing will have 

 occurred during the first 6 hours of the exposure and the building may 

 be ventilated after that time, as a minimum, has elapsed, although 

 it is better to wait 12 hours or longer. In cases of long exposures 

 the vapors will have diffused so tuWy by the end of 24 hours that 

 there will be no danger to anyone entering the building to open it for 

 ventilation. If, however, it is found that the gas is still very strong, 

 the respiration bag, as described on page 6, should be used. The 



