February, '10] WOGLUM : SODIUM CYANIDE 85 



VALUE OF SODIUM CYANIDE FOR FUMIGATION 



PURPOSES 



By R. S. WoGLUM, Special Agent. Bureau of Entomologt/. U. 8. Department 



of Agriculture 



For almost three years the United States Bureau of Entomology 

 has been conducting in California an investigation of the use of 

 hydrocyanic-acid gas for the fumigation of citrus trees, with the 

 object of placing this very extensive practice on a more economical 

 and effective basis. A preliminary report on results of one problem 

 taken up during this investigation is given in the present paper. 



With the exception of an instance noted below, cyanide of potas- 

 sium has been the chemical used both in this country and abroad in 

 generating hydrocyanic-acid gas for all fumigation purposes, includ- 

 ing the fumigation of orchards, nursery stock, greenhouses, mills, 

 dwellings, infested fruit, seeds, etc. There is, however, a second 

 cyanide compound, cyanide of sodium, which is used more extensively 

 for other general commercial purposes than the cyanide of potassium. 



C. P. Lounsbury, Government Entomologist of Cape Colony, was 

 the first to call attention in literature to sodium cyanide for fumiga- 

 tion, when, in 1905, after stating that the sodium compound yields 

 more gas from a given weight than the potassium (the actual yield is 

 between one fourth and one third greater), he stated that the former 

 might possibly within a few years be used instead of the potassium 

 salt. This supposition seems to have been based entirely on the con- 

 sideration of the greater yield of *gas of the former. 



Early in the investigation it was learned that, unknown to the con- 

 sumer, sodium cyanide has been used to a limited extent in California 

 in practical orchard work for a number of years. This was a 99-100 

 per cent product instead of the 132^ per cent which is the gas strength 

 of the chemically pure sodium salt. Sodium cyanide has been sold 

 under the name '' American" cyanide, in distinction to "German" 

 cyanide, which is the 98-99 per cent potassium salt commonly em- 

 ployed. The consumers have considered both brands to be potassium 

 cyanide, the popular distinction being that one was made in America 

 while the other was imported from Germany. Although the 99 per 

 cent sodium cyanide contained fully as much cyanogen as the regular 

 98-99 per cent potassium cyanide, as well as being less expensive, yet 

 it has had a very limited use, due to the inferior results obtained with 

 it against the pests of citrus trees. Furthermore, extensive experi- 



^Styled 132 per cent to indicate ttiat 100 pounds sodium cyanide equals in 

 gas product 132 pounds of potassium cyanide. 



