FUMIGATION" OP ORNAMENTAL GREENHOUSE PLANTS. 7 



MIXING THE CHEMICALS. 



After the generators have been distributed throughout the green- 

 house, and before the chemicals have been mixed, the cyanid should 

 be weighed accurately and the proper amount for each generator 

 placed in a paper bag near the generator. The chemicals should be 

 mixed invariably in the following manner : First, measure and place 

 in each generator the amount of water required ; second, measure and 

 place in each generator the amount of sulphuric acid required ; third, 

 drop the cyanid into the diluted warm acid in each generator, close 

 the covers, immediately leave the house, and post a danger sign on the 

 closed door. The cyanid should be dropped gently, not thrown, into 

 the generators, and the operator should begin at the generator 

 farthest from the door and work toward the door. In case there are 

 two rows of generators the cyanid should be dropped simultaneously 

 by two operators. As little time as possible should elapse between 

 the addition of the acid and the addition of the cyanid, as the heat 

 which is liberated by the mixing of the acid and water assists in the 

 generation of the gas. 



The residue left in the generators after fumigation should be 

 buried or poured into a sink and the generator washed before being 

 stored for future operations. 



NUMBER OF GENERATORS TO BE EMPLOYED. 



The number of generators will depend largely upon the size of the 

 house, and they should be so arranged that the gas will be uniformly 

 distributed throughout the inclosure. To secure this advantage, it is 

 advisable that a number of generators be used rather than one large 

 generator. Generators should be spaced from 20 to 25 feet apart, 

 and in case of a light wind a few extra generators should be placed 

 on the windward side of the house. An ounce to each jar is as small 

 a dose as is practicable, unless the generators are well rounded inside 

 at the base or well tilted. 



EXPOSURES. 



Short exposures with a greater strength of gas have been found 

 more satisfactory than a weaker strength of gas overnight. In fact, 

 better results will be gained if the exposures do not exceed one to two 

 hours. An exposure of one hour is satisfactory in most instances. 

 Short exposures also have the additional advantage of permitting 

 the house to become thoroughly aerated previous to the rising of 

 the sun. 



