54 CIRCULAR 36 9, U. S. DEPARTMENT OF AGRICULTURE 



tube extending to the bottom of the tank. This tube is larger than 

 that of the shipping cylinder and allows the more rapid flow of gas 

 needed. Gas-inlet valves (half-inch brass) and a pressure gage are 

 also located on the top-central part of the cylinder. From the tank 

 connection of the gage a bypass of quarter-inch copper tubing sup- 

 plied with a valve is connected to the gas-outlet line between the 

 outlet valve and the manifold of the piping system of the building 

 being fumigated. This bypass allows the pressure developed by the 

 transfer of the hydrocyanic acid from the shipping cylinder to the 

 applicator to escape into the manifold, thus facilitating the filling of 

 the applicator. 



CHLOROPICEIX AS A MUX FTJMIGANT 



For fumigation with chloropicrin the mill should be prepared in 

 the same way as for fumigation with hydrocyanic acid, except that 

 items 1 to 14 of the directions for preparing "the mill after the ma- 

 chinery is stopped can be omitted. Each piece of machinery is 

 treated separately, and in addition the open space of the mill is 

 treated at the rate of 1 pound of chloropicrin per 1.000 cubic feet. 



Sufficient data have not yet been obtained for making definite rec- 

 ommendations of dosages to fit the varying conditions encountered in 

 general mill fumigation. As a rule, however, the following dosages 

 recommended by the manufacturers of chloropicrin will give satis- 

 factory results: 



Dosage Table for Treating Milling Machinery 



All bins, including packer bins, feed and bran 



bins, and screening bins 1 pound per 1,000 cubic feet. 



Elevator legs 8 to 9 ounces each, in up- 

 stream side. 



All reels, purifiers, dusters, scourers, and con- 

 veyors 5 to 6 ounces each. 



Square sifters 2 to 3 ounces each. 



Rolls 1 ounce each. 



Separators 2 to 3 ounces each. 



Flour agitators 2 ounces each. 



Grinders for screenings and bran 2 ounces each. 



Buhr mill 2 ounces. 



The proper quantity of chloropicrin for each floor of the mill 

 should be measured out from the 100-pound cylinders into quart glass 

 bottles or gallon containers and distributed before the fumigation is 

 begun. The measuring should be done outside the building so that 

 the fumes will be dissipated in the open air. However, men doing the 

 measuring or handling the chemical should wear gas masks equipped 

 with the proper canisters for this gas. The quart bottles should 

 be graduated so that the correct dosage for each piece of machinery 

 can be applied quickly. One pound of chloropicrin equals 9% fluid 

 ounces. 



The fumigators start at the top of the mill and work down, treat- 

 ing all the machinery and leaving the elevator boots until the last. 

 Each f umigator must wear a mask equipped with a canister espe- 

 cially adapted to protect against the vapors of chloropicrin. 



The machinery is treated by sprinking from the quart bottle di- 

 rectly inside each machine or, if this is impractical, by pouring it in 

 through a hole in one end. Aluminum sprinkler corks can be at- 

 tached to the bottles as they are used. In open mill space the 



