SODIUM CYANID FOR FUMIGATION PURPOSES. 87 



1-1 h-2 formula. The dosage strength was equivalent to that of 

 schedule No. 1 of potassium cyanid. The operation was carried out 

 under the guidance of the foreman of the crew exactly as work is 

 done by any commercial outfit. Several months later an examina- 

 tion was made of a large number of trees located promiscuously 

 throughout the orchard. Live purple scales were seen on only one of 

 the trees examined, and on this much of the fruit was infested at the 

 time of fumigation. This is the most successful work the writer has 

 ever seen done by a practical outfit with gas of a strength equivalent 

 to schedule No. 1 of potassium cyanid. 



Several hundred pounds of this high-grade sodium cyanid were used 

 by another practical outfit in fumigating orange and lemon trees. 

 These fumigators were as satisfied with this cyanid as with the regu- 

 lar potassium cyanid. 



From the results of field work in this investigation it has been found 

 that the use of a high-grade, or almost chemically pure, sodium cyanid 

 produced exactly as perfect a generation of gas in all cases as the use 

 of a similar grade of potassium cyanid; in the majority of cases where 

 used the generation was apparently superior to that from a potassium 

 cyanid. 



ACTION OF SODIUM CHLORID. 



The above recommendations are for a high-grade sodium cyanid — 

 one almost 133 per cent pure. Experience in California with a 98 

 to 100 per cent sodium cyanid has proved unsatisfactory. The rea- 

 son is given herewith. Chemical analyses have shown that practi- 

 cally all commercial potassium and sodium cyanids contain more or 

 less common salt, which is technically spoken of as sodium chlorid. 



Newell, 1 in 1905, pointed out that sodium chlorid, when present in 

 the reaction producing hydrocyanic-acid gas, causes a secondary 

 reaction which hberates an acid called hydrochloric acid, and that 

 this liberated hydrochloric acid immediately attacks the hydrocyanic- 

 acid gas, decomposing it to a great extent. In order to ascertain more 

 thoroughly the status of this salt Mr. McDonnell carried on a large 

 amount of experimental work. These results not only showed con- 

 clusively that the presence of sodium chlorid results in a decom- 

 position of the hydrocyanic-acid gas, but also that if a sufficiently 

 large percentage of sodium chlorid is present the decomposition will 

 be so great as to result in little if any hydrocyanic-acid gas. The 

 conclusion to be drawn from these experiments is that the cyanids 

 suitable for fumigation work should be practically free of sodium 

 chlorid. 



The serial numbers 6523-6529 in the table on page 92, Part III of 

 this bulletin, are samples of cyanids which have been used to some 



1 Bui. 15, Ga. State Bd. of Ent., 1905. 

 67330°— Bull. 90—12 7 



