CYANIDE FUMIGATION OF MUSHROOM HOUSES 3 



there, out of any standing water, the operator walked up the length of 

 the central alleyway, carefully pouring the acid into the generators as 

 he went. Upon reaching the rear of the house he took up the bags of 

 cyanide and walked toward the front of the house where the door 

 was held open, dropping a bag of cyanide into each generator as he 

 passed it. In the case of a double house, two men would be required, 

 as for fumigating with calcium cyanide. 



FUMIGATION WITH LIQUID HYDROCYANIC ACID 



Liquid hydrocyanic acid requires special apparatus which consists 

 of a cylinder of the liquid, a pump by means of which a pressure may 

 be built in the cylinder, a pressure gage to determine the pressure, 

 mounted upon a " delivery cross " which enables the operator to regu- 

 late the flow of gas and to blow the line clear, a %- or ^-inch delivery 

 line equipped with spray nozzles, and a platform scales upon which to 

 weigh the quantity of gas used. In the present experiments, a ^-inch 

 delivery line was run along the central alleyway, on or suspended 

 from the supports of the center walk, the nozzles directed downward. 

 The dosage, for comparative purposes, was one-fourth pound per 1,000 

 cubic feet of air space, this being equivalent to the volume of gas 

 capable of being released by 1 pound of calcium cyanide or one-half 

 pound of sodium cyanide. 



After fumigation by any of these methods the house was closed 

 tightly and left so for several hours, or until analysis showed that the 

 gas was nearly gone from the house. Analyses were made at intervals 

 to determine the concentration of gas. The glass tubing through 

 which samples were drawn for analysis was led into the house through 

 holes near the door, the intake of each being about 12 feet from the 

 end of the house. 



The time intervals of sampling were calculated from the minute that 

 actual fumigation operations commenced, that is, when the operator 

 dropped the first bag of sodium cyanide, or the first handful of cal- 

 cium cyanide, or turned the release valve on the delivery cross of the 

 cylinder of liquid hydrocyanic acid. 



DISTRIBUTION OF THE GAS 



The temperature in the upper one-half or two-thirds of the mush- 

 room house at peak heat is usually high enough either to kill all 

 pests or drive them from the manure. In most cases when so driven 

 out, they fall to the floor and may survive there to reinfest the upper 

 beds. For this reason it is important that the lower third of the 

 house receive a good fumigation. Hydrocyanic acid gas, being 

 lighter than air, ordinarily rises to the top of the house and remains 

 there, the floor receiving very little benefit from it. This is especially 

 true of the hot gas from the acid generation. Fortunately, the fans 

 may be left running in the house during cyanide fumigation, making 

 possible a fairly uniform distribution of gas. For distribution of 

 temperature the fans, 2 to the standard house of 65 feet, are placed 

 on the floor in the central alleyway with the air current directed up- 

 ward toward the ceiling of the house. During fumigation, however, 

 it is better to have 3 or 4 fans running within the house, as the dis- 

 tribution of the gas must be as rapid as possible. If the fans were 



