68 THE MONTHLY BULLETIN. 



each quality and variety figured separately, one grower receiving as 

 much as the other for the same quality and grade of fruit. In this 

 manner the grower has more than one outlet for his fruit : cannery, 

 Eastern and local trade as well, and a better and more satisfactory 

 price is obtained for the fruit from all. 



NEW FUMIGATING MACHINES. 



By Geo. P. Gray,* University of California, Berkeley, Cal. 



HISTORICAL. 



It is a rather interesting fact that the most recent development in 

 fumigation practice, the use of an outside generator for the production 

 of hydrocyanic acid gas, is a return to first principles. 



In what is believed to be the first printed report made public on the 

 fumigation of citrus trees by means of hydrocyanic acid gas, Mr. F. "W. 

 Morse^ gives the following description of the apparatus used to generate 

 the gas: 



"The generator in which the gases were produced consists of a 

 heavy sheet-iron cylinder, 11 inches in diameter and 13 inches 

 high. The bottom rests on a plank, and to the top is fitted a 

 movable cover suspended in a frame by a bench-screw. Into the 

 cover are fitted pieces of gas pipe — one for the exit of the gas 

 toward the tent and the other, connected with a pump, carries 

 the gas which returns from the tent. Two small reservoirs are 

 also inserted in the cover; in these are contained the solutions 

 which are to flow into the generator for the production of the 

 gas. 



"In order to establish circulation and to force the gas into the 

 tent, a pump is used, which also serves to exhaust the gas from 

 the upper part of the tent and to force it again through the 

 generator. ' ' 



Mr. D. W. Coquillett, who was actually the first one to demonstrate 

 the value of the gas as a fumigant against scale insects, also used a 

 generator outside of the tent for the production of the gas, in his early 

 experiments. The apparatus used by both these experimenters were 

 rather cumbersome affairs. The most convenient manner of bringing 

 together with the sulfuric acid and cyanide was to have the cyanide dis- 

 solved in water and this solution and the acid were brought together in 

 the generator. It was found that if the gas were produced in the wet 

 way, i. e., having the cyanide in solution, considerable foliage injury 

 usually resulted. The foliage injury was accounted for by the production 

 of ammonia as a result of adding the cyanide to the acid when the former 

 was in solution. It was later found that very little injury resulted 

 if the acid were added to the solid cyanide, i. e., in the dry way. During 

 later experiments conducted at the orchard of Mr. A. D. Bishop by 

 Mr. Coquillett, the outside generator was discarded in favor of the 

 simpler method of generating the gas by throwing the solid cyanide into 

 diluted acid contained in a pot under the tent. This simpler method of 



♦Address before the State Fruit Growers' Convention, Los Angeles, California, 

 November 10 to 14, 1914. 



'Cal. Agr. Exp. Sta. Bull. No. 71, June, 1887. 



