12 



BULLETIN 872, U. S. DEPARTMENT OF AGRICULTURE. 



properly informed and careful person. Success in the use of hydro- 

 cyanic-acid gas is in proportion to the tightness of the mill to 

 be fumigated. Many old loosely constructed mills can not be fu- 

 migated successfully, even by an expert fumigator, because they 

 will not hold the gas sufficiently long. In such mills one can not 

 hope to do more than reduce the moth temporarily by any one fumi- 

 gation. In tight structures two thorough fumigations applied dur- 

 ing warm weather within 

 a short time of each other, 

 as discussed on page 27, have 

 been known to exterminate 

 the moth. In rare cases one 

 fumigation has exterminated 

 the moth. 



Precautionary Measures. 



Although it has been stated 

 above that no mill concern 

 should attempt fumigation 

 without the assistance of a 

 chemist, entomologist, or 

 other person well informed 

 regarding the process, atten- 

 tion should be called to sev- 

 eral precautions that must 

 be taken to guard against fa- 

 talities arising from inex- 

 cusable carelessness and igno- 

 rance. Very few deaths have 

 occurred as a result of fu- 

 migation with hydrocyanic- 

 acid gas as a mill fumigant, 

 and those that have oc- 

 curred have been due to 



Fig. 7. — Wooden oil barrel, well soaked with 

 water previous to use in fumigation, set 

 in galvanized iron washtub partially filled 

 with water to which have been added sev- 

 eral handfuls of sal soda. 



criminal neglect on the part of those responsible for the fumiga- 

 tion. 



Where mills are in buildings well isolated from other buildings, 

 owners need not consider neighbors in their plan for fumigation, but 

 when the fumigation is to be conducted in one of a series of buildings, 

 such as occur in city blocks, owners of property immediately adjoin- 

 ing must be informed of the intention to fumigate and arrangements 

 made with them whereby they will be ready to vacate their stores or 

 offices should the fumes penetrate the intervening walls. The odor 

 of hydrocyanic-acid gas is easily detected, and the person in charge of 



