THE MYCOGOXE DISEASE OF MUSHROOMS AND ITS CONTROL. 19 



24 by 100 feet, the usual size of mushroom houses, at least three 

 receptacles should be used in which to generate the gas. It does not 

 matter what the material of the receptacles may be, for the formalin 

 has no corrosive action, but the heat of the chemical reaction, when 

 potassium permanganate (permanganate of potash) is added to the 

 formalin, might break glass receptacles. Half barrels, wash tubs, and 

 iron or earthen receptacles are suitable, but it is advisable to select 

 containers in which the diameter of the top is greater than that of 

 the base. The formalin should cover the potassium permanganate 

 when it is placed in the receptacle, which should be deep enough to 

 insure the formalin from splashing over as a result of the vigorous 

 chemical action. 



The proper amount of formalin is measured and divided among 

 the number of receptacles to be used in each house, while the proper 

 proportion of potassium permanganate to be added to the formalin 

 in each receptacle is carefully weighed out into paper or cloth bags. 

 It will be found more satisfactory and the possibility of error may 

 be avoided if like amounts of formalin and potassium permanganate 

 are placed in each receptacle. If convenient, receptacles of a uniform 

 size should be selected. 



The weighing and measuring of the chemicals should be accom- 

 plished as quickly as possible after the receptacles containing the 

 formalin are placed in the house. It is advisable to weigh the potas- 

 sium permanganate into the bags first and then to measure the for- 

 malin for the respective receptacles, since considerable gas will be 

 given off from the formalin and the house being almost air-tight, 

 extreme physical discomfort due to the formaldehyde gas might 

 result. The receptacles containing the formalin are then placed in 

 position in the aisles of the house. In average-sized houses it will 

 be sufficient to place the receptacles in the center aisle, but in larger 

 houses the gas must be more evenly distributed by placing some of 

 the receptacles in the several aisles. There will be required as many 

 persons to place the bags of potassium permanganate in the formalin 

 receptacles as the number of aisles in which the receptacles have 

 been placed. 



A bag of potassium permanganate is placed beside each receptacle 

 containing the proportionate amount of formalin. When everything 

 is ready, the operator in each aisle, if there are receptacles in more 

 than one aisle, goes to the farthermost receptacle in that aisle and 

 places the bag of potassium permanganate in the formalin, the 

 operation being simultaneous in each aisle. Egress is made through 

 the door at the end of the aisle, which is quickly closed and tightly 

 sealed. 



The operation should be accomplished as quickly as possible, and 

 care should be taken to prevent accidents, for inhaling large quantities 



