36 Texas Ageicultur.4lL Experiment Station 



times as heavy as air. This is a point to be remembered in its use, 

 since it goes first to the bottom of whatever it is confined in. When 

 mixed with air, it becomes highly inflammable and sometimes explosive. 

 Such a mixture of air and bisulphide gas may be exploded by even a 

 spark such as might be made by hitting a nail with a hammer. The 

 liquid, upon evaporation, leaves a residue of impurities. Its rate of 

 evaporation is in proportion to the temperature and the area of the 

 exposed surface. Its efficiency is the greatest with the rapid evapora- 

 tion, and this is secured in relatively warm weather, but artificial heat 

 must never be used to hasten its changes into gas. Carbon bisulphide 

 is obtainable from practically every druggist. 



When carbon bisulphide is to be used for fumigation of infested ma- 

 terial, the greatest precaution should be used to keep all fire, such as 

 lights, cigarettes, etc., away from the liquid and where it is being used. 

 For this reason it is well to take the material that is to be fumigated 

 out-of-doors and at least 100 feet away from any building. The in- 

 fested material should be placed in supers or hive bodies if possible. 

 These are piled as high as is convenient and all cracks between the 

 containers made as nearly gas-proof as possible. Especially should the 

 bottom be tight. A good plan is to place an inverted hive cover on. 

 the ground, lay a piece of canvas over it and then tier up the supers 

 on this. After the pile has been completed, an empty super should be 

 put on top, in which should be placed a large shallow pan. Into the 

 latter the bisulphide is to be poured. When all is in readiness, pour 

 the bisulphide into the pan, and immediately put a hive cover on the 

 top of the tier to confine the gas. This operation is best performed in 

 the evening, and the pile of supers should be left intact the following 

 morning. When the supers are taken down the confined gas will escape 

 immediately, even before they can be carried separately into a building. 



The results of fumigating infested material with carbon bisulphide 

 is shown in table 27. 



