low dish on top. Both the top and bottom of the cylinder were pro- 

 vided with leather packing and covers which were screwed on tight. 

 The weevils were inclosed in perforated boxes as in the preceding 

 experiments. The results show the failure of the gas, when applied 

 at the rate of 10 pounds to 1,000 cubic feet, to penetrate sufficiently 

 to kill weevils buried beneath 4^ or more feet of seed. At 3 feet, 

 however, 7.3 pounds per cubic foot killed the insects. That small 

 quantities of gas penetrated the full depth of the cylinder is shown by 

 the death of the house flies. 



These experiments seemed to indicate the futility of the use of car- 

 bon bisulphid in an unvolatilized form, and it was therefore deter- 

 mined to test it in an artificially volatilized form, as shown in the 

 following experiments. Credit for this idea should be given to the 

 writer's principal assistant, Dr. W. E. Hinds, who has experimented 

 extensively with carbon bisulphid.'* 



Experiment wUh carbon bisulphid volatilized artificially in cylinder 70 by 12 incJies. 



In this experiment, by means of special apparatus, a current of air 

 was passed through the liquid carbon bisulphid and the resulting vapor 

 was driven through connecting tubing into a section of iron gas pipe 

 which could be forced through the seed to the bottom of the cylinder, 

 and which was gradually withdrawn during the application. The dif- 

 fusion of the vapor under pressure through the mass of seed was very 

 rapid and, as will be noted by a comparison of the two last tables, the 

 amounts of carbon bisulphid used were far more efficient. 



This experiment was followed by a number of others in forcing the 

 gas into the seed in 100-pound sacks. It was found quite practicable 

 in this way to kill the weevils contained at any point in the sacks, pro- 

 viding the carbon bisulphid was used at the rate of 8 pounds per 1,000 

 cubic feet and left for forty hours. 



MEANS AND METHOD FOR SUCCESSFUL FUMIGATION OF COTTON 



SEED. 



The following plan for this work is proposed: A tight matched- 

 board box should be provided having sides 4 feet high, open on top, 



84234- 



oSee Farmers' Bulletin No. 145. U. S. Dept. of Agr. 

 -Bull. 209—09 2 



