76 THE MONTHLY BULLETIN. 



entirely satisfactory. These experiments were conducted under labora- 

 tory conditions and upon small samples and entirely in glass containers. 

 They, therefore, can not be taken as conclusive proof of the uniformity 

 of generation under the conditions maintained in the operation of the 



machines. 



IMPORTANCE OF USING PURE CYANIDE. 



A publication of the United States Department of Agriculture- points 

 out the decomposing effect of sodium chlorid (common salt) when 

 present in commercial cyanides and strongly advises against the use 

 in fumigation practice of cyanides containing in excess of one per cent 

 of sodium chlorid. 



While this view is not held by the Insecticide Laboratory of the 

 University of California^' when the solid lumps of cyanide are thrown 

 into the diluted acid according to the customary procedure in the pot 

 system of cyanide generation, the experiments reported in the publica- 

 tion last referred to do show that there is a very serious decomposition 

 if the salty cyanide is dissolved previous to its addition to the acid. In 

 this latter matter the recommendations of the two publications are in 

 agreement. 



It is very important, therefore, that pure cyanide only be used in 

 connection with the machines. The presence of sodium chlorid (common 

 salt) in the cyanide used would result in very material decomposition 

 of the hydrocyanic acid. 



INVESTIGATIONS OF THE INSECTICIDE LABORATORY. 



The Insecticide Laboratory has received numerous enquiries from 

 men interested in citrus fumigation, about the m.erits and demeritsof 

 the fumigation machines. Previous to June of this year, the Insecticide 

 Laboratory had no direct information about the machines based upon 

 personal observation. The opinions expressed were largely theoretical 

 and the result of hearsay. The matter was therefore taken up with 

 Professor H. J. Quayle, entomologist of the Citrus Experiment Station 

 at Riverside, and arrangements were made for a brief study of the 

 machines. Through the courtesy of the Limoneira Company, which was 

 the first to purchase a model of the machine this season. Professor 

 Quayle and the speaker were invited to come to the ranch at Santa 

 Paula, where ample opportunity and facilities would be provided for a 

 study of the machine as actually operated in the field. A very extended 

 study of the machine was not attempted, but some points of immediate 

 interest were investigated and conclusions arrived at which will be 



briefly given. 



Graduation. 



There was some doubt expressed about the logical graduation of the 

 measuring cylinders and this point was investigated. 



The regular formula for fumigation work, that is, one ounce by 

 weight of sodium cyanide to two fluid ounces of water, was tested out 

 in regard to the increase in volume of the water from the dissolved 

 cyanide. For practical purposes, it was shown that the water was 

 increased 25 per cent of its volume, that is, an ounce of cyanide and two 

 ounces of water occupy a volume of 2| fluid ounces when solution is com- 



=Woglum, R. S., McDonnell. C. C, U. S. D. A., Bur. Ent. Bui. 90, Parts II and III. 

 ^Colby, G. E., and Gray, G. P., Cal. Agr. Exp. Sta. Cir. 72. 



