146 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



(11) Calandra oryza L. : Asphyxiated within 30 minutes. In the 

 same jar was Silvanus surinamensis and Triholium confustim. 



(12) Bean weevil {Bruchus quadrimaculatus Boh.) : Asphyxiated 

 within 30 minutes. 



All of the material referred to above was left untouched for approx- 

 imately 20 hours, at the end of which time no sign of life or evidence 

 of possible resuscitation was manifested on exposure to air, and 

 there were no later revivals. No signs of life Avere afterwards seen 

 in the infested wood material, and a thorough examination made two 

 months after treatment by Doctor Hopkins indicated that the insects 

 had been reached in the Avood and killed. 



At the same time various objects were placed in the building to 

 determine the bleaching effect of the gas — a good many colored 

 papers and a good many fabrics, representing light-colored cotton 

 linings and silk and cotton linings, black, and also men's tailoring 

 goods of various colors and qualities. No bleaching effect w^as noted 

 whatever in the heavier cloths. Some of the lining cottons showed 

 slight bleaching. The papers were practically unbleached, except 

 one of pink shade. The bookbinding cloths were very slightly 

 bleached, not enough to be especially noticeable or to injure the 

 appearance of the bindings. A highly polished bit of brass was com- 

 pletely darkened and tarnished. 



Experiment No. 9. 



This experiment w^as to determine the possibilities of penetration 

 of a low percentage of gas, between 5 and G per cent, ending at the 

 latter amount. Small bags of infested grain were placed at the 

 bottom of an air-tight zinc-lined box having a depth of 18 inches and 

 a capacity of 3 or 4 bushels. Similarly small bags of infested grain 

 were placed at the bottom of earthenware crocks having an inside 

 depth of 14 inches. The gas could only get at these insects by pene- 

 trating through the grain directly from the top, 18 inches in one case 

 and 14 in the other. This was necessarily a pretty severe test, inas- 

 much as there was no possibility of circulation of air. The gas 

 was kept under pressure for one-half hour after reaching 6 per cent 

 to increase the possibilities of penetration. The ap])aratus was then 

 disconnected and the building left closed overnight for a total of some 

 22 hours. The gas in the building was tested from time to time 

 after stopping the generator. After one-half hour per cent gas 

 w^as still found, and the same Avas true after an hour's time. After 

 2 hours the percentage had fallen to 5 per cent, and at the time of 

 the opening of the building in the morning of the following day 

 there was still at least 1 per cent of gas present. 



Results. — Neither in the ease of the zinc-lined box nor the crockery 

 jars had the gas penetrated very deeply into the grain, and the insects 



