156 FUMIGATION METHODS 



chance to use the gas in a granary and storehouse. 

 The results were so gratifying we decided to apply the 

 same methods to a modern mill, if an infested one 

 could be found and the owner would consent to the 

 experiment. Two infested mills where we could try 

 the gas on a large scale were soon found. Both 

 contained three stories with basement and attic. One 

 was 70 by 40 feet and the other 50 by 50 feet. Before 

 filling an entire building with the gas, we decided to 

 confine our experiment to one floor. All arrange- 

 ments were made with a Pennsylvania miller and final 

 directions were sent for the work. The first charge 

 was set off June 10, 1899, using five pounds of 

 potassium cyanide, an equivalent of o. 10 gramme 

 cyanide per cubic foot of space enclosed. 



Five days later the following letter was received 

 from the owner: " We made use of the chemicals sent 

 us, as directed, on the loth instant, and had some 

 success, at least enough to convince us that through 

 its use we can retain possession of our mill. Most of 

 the weevil on the first floor are either on the floor or 

 very close to it, and we find that a good many of them 

 escaped punishment. In the rooms above the first 

 floor we will have a better chance at them, they being 

 higher up in places where we can not get at them 

 with anything but gas. We would like to have you 

 arrange to send us enough of the potassium cyanide to 

 go through our mill from the first floor up. Any 

 information you can give us concerning the second 

 treatment will be greatly appreciated. We found a 

 dead cat on the mill floor when we went in after airing 

 the room thoroughly. ' ' 



