A COVER FOR FUMIGATION GENERATORS. 



57 



tent. It is attached to the generator by hinges of stout copper wire 

 secured by a key bolt passing through the handle. The cover is 

 raised by a slight pressure of the thumb on a projecting piece which 

 is curved in such a manner that the cover will remain in an upright 

 position when so required. Wlien the generator is emptied of its 

 contents, the cover swings clear by its own weight. A glance at the 

 illustration will satisfy the practical fumigator that it is adapted to 

 all the requirements of rapid work in the dark, while its use has 

 demonstrated that it is simple, strong, and durable. It is very 

 possible that if the copper cover were lined with a thin covering 

 of lead its durability 

 would be increased. 



A common result of 

 the use of heavy do- 

 sages of fine fragments 

 of cyanid is the burn- 

 ing and ultimate drop- 

 ping of many of the 

 leaves directly above 

 the generator in the 

 pathway of the rapidly 

 rising gas. This result 

 is usually spoken of as 

 the "chimney" effect. 

 The generator cover 

 eliminates this "chim- 

 ney" burning. 



A second and highly 

 important point is the 

 effect of open gener- 

 ators on the tent. 

 The outer part, or skirt, as it is sometimes called, of fumigating 

 tents is constantly being perforated with small holes, even when 

 used by the most carefid of workers. We have noticed this effect 

 to some extent in our own outfit, which we believe to be as carefully 

 handled as any fumigation outfit could be. These holes are known 

 to be acid burns. A few simple tests have demonstrated conclu- 

 sively that many of these acid holes are due to acid carried along 

 with the escaping gas and reaching that part of the tent nearest 

 the generator. By placing large pieces of canvas in the path of gas 

 escaping from open generators in which dosages similar to those 

 often used in field work are employed, it was found that drops of 

 acid reached the canvas as high as 5 feet from the ground. The 

 writer has frequently seen generating vessels placed not more than 

 2 feet inside the tent. At such a distance one can readily see that 



Fig. 20.— Zinc-covered top for protecting cyanid in the field. 

 (Original.) 



