396 INSECTS AFFECTING VEGETATION 



life, is heavier than air and settles and fills any compartment or bin 

 in the top of which the liquid is placed. It may be distributed in 

 shallow dishes or tins or in saturated waste on the top of grain in 

 bins, and the gas will settle and permeate throughout the mass of 

 the grain. In large bins, to hasten and equalize the operation, it is 

 well to put a quantity of the bisulphid in the center of the grain by 

 thrusting in balls of cotton or waste tied to a stick and saturated 

 with the liquid, or by means of a gas pipe loosely plugged at one end, 

 down which the liquid may be poured and the plug then loosened 

 with a rod. Prof. H. E. Weed reports that in Mississippi the chemi- 

 cal is commonly poured directly onto the grain. In moderately 

 tight bins no further precaution than to close them well need be 

 taken, but in open bins it will be necessary to cover them over with 

 a blanket to prevent the too rapid dissipation of the vapor. The bins 

 or buildings should be kept closed from twenty-four to thirty-six 

 hours, after which a thorough airing should be given them. 



Limited quantities at a time may often be advantageously sub- 

 jected to treatment in small bins before being placed for long stor- 

 age in large masses, and especially whenever there is danger of intro- 

 ducing infested grain. The bisulphid is applied at the rate of 1 

 pound to the ton of grain, or a pound to a cubic space 10 feet 

 on a side. 



In the case of mills, elevators, or larger granaries the applica- 

 tion may be best made on Saturday night, leaving the building 

 closed over Sunday, with a watchman without to see that no one 

 enters and to guard against fire. The bisulphid should be first dis- 

 tributed in the upper story, working downward as rapidly as pos- 

 sible to avoid the settling vapor, using the substance very freely in 

 waste or dishes at all points of infestation and over bins through- 

 out the building. If the building be provided with an exterior 

 means of descent (such as a fire escape) it would be preferable to 

 begin with the lower story and work upward. 



This insecticide may also be used in other stored products, as 

 peas, beans, etc., and very satisfactorily where the infested material 

 can be inclosed in a tight can, chest, or closet for treatment. It may 

 also be employed to renovate and protect wool or similar material 

 stored in bulk. The bisulphid costs, in 50-pound cans, 10 cents 

 per pound, and in small quantities, of druggists, 25 to 35 cents per 

 pound. 



The bisulphid may be more freely employed with milling grain 

 than with that intended for seeding, since, when used excessively, it 

 may injure the germ. It must always be remembered that the 

 vapor is highly inflammable and explosive, and that no fire or 

 lighted cigars, etc., should be in the building during its use. If 

 obtained in large quantities it should be kept in tightly closed ves- 

 sels and away from fire, preferably in a small outbuilding. 



While this gas is not especially dangerous to human beings, 

 care should be taken to avoid unnecessary inhalation. It has a 

 slight suffocating effect, and if inhaled for some time produces dizzi- 



