84 HYDROCYAXIC-ACID GAS FUMIGATION IX CALIFORNIA. 
tables. The quantities of acid and water for a tree of any given size would remain 
the same, but the weight of cyanid for use with any given measure of acid would have 
to be reduced one-fourth. 1 
This last statement of Prof. Lounsbury assumes that the reaction 
would require the same proportion of chemicals as with potassium 
cyanid, an assumption winch the earlier chemical work of this inves- 
tigation shows to be without any foundation. 
The potassium cyanid used in California for fumigation is manu- 
factured in Germany, and is popularly styled "German" cyanid. 
This is in distinction to a grade of cyanid made in this country, 
termed "American" cyanid, winch has had an occasional and limited 
usage in California for a number of years. This so-called " American ' ' 
cyanid has been popularly believed to be the very same kind as the 
imported potassium cyanid. Such a conception has been misleading, 
for chemical analyses have shown it to be not potassium cyanid but a 
cyanid of sodium equivalent to a potassium cyanid of 98 to 100 per 
cent purity. 
Tins 98 to 100 per cent sodium cyanid was found by funhgators to 
be inferior to the regular potassium salt ordinarily employed. It was 
of very hard composition and generated so slowly that large propor- 
tions of acid were commonly used in an attempt to hasten the reaction. 
Some fumigators used large quantities of water, believing this was 
necessary in order to secure the best results. Tests performed by the 
writer showed that frequently it would require 10 to 15 minutes before 
all the available gas was expelled from a generation of this cyanid. 
Furthermore, the writer was informed by the president of a firm which 
supplies most of the cyanid used in California, that extensive chemical 
experiments carried on in its laboratory indicated that this sodium 
cyanid produced a less satisfactory generation than did potassium 
cyanid, and from these considerations he believed its use would never 
be economical. The work of the firm also indicated that large pro- 
portions of water were necessary for a satisfactory and rapid reaction. 
Under the belief that sodium cyanid had not received sufficiently 
exhaustive tests, the writer ignored all local unfavorable evidence, 
and, in December, 1908, outlined in detail a broad series of chemical 
experiments to secure reliable data, with reference to this salt, on the 
various factors winch might enter into hydrocyanic-acid generation. 
This outline was submitted to the Bureau of Chemistry of this depart- 
ment for execution. Mr. C. C. McDonnell, under the direction of Dr. 
J. K. Haywood, Chief of the Miscellaneous Division, made a very 
careful and elaborate series of determinations, and in August, 1909, the 
results of these tests were submitted to the writer in a carefully pre- 
pared manuscript, which forms Part III of this bulletin. These 
results are used in part in the preparation of the present paper. 
1 Office of Government Entomologist. Department of Agriculture, Cape ol Good Hope. ''Cyanid Gas 
Remedy for Scale Insects.'' Jul}-, 1905. 
