CHEMISTRY OF FUMIGATION. 99 
(HCN)2 or H— N=C— H. 
C=N 
The first product formed being imidoformylchlorid 
H— N=C— H, 
A, 
which compound immediately combines with a second molecule of 
HCN thus 
HN NH 
H— N=C— H + HCN = "^C— C^ 
forming an imid-chlorid. This in turn takes up one or two molec- 
ular proportions of HC1 with the formation of compounds of the 
following constitution : 
HN. ^NH H 2 N\ .NH 
JC—Cf +HC1= ^c— cc 
IV XJ1 H I Cl 
HN. .NH H 2 N X /NH 2 
^C— Cf + 2HC1 = >C— C< 
u/ X C1 B< I I X C1 
Cl Cl 
These compounds decompose in the presence of moisture, as before 
described, mainly into formic acid and ammonium chlorid. 
EFFECT OF THE PRESENCE OF SODIUM CHLORID IN CYANIDS ON 
THE YIELD OF HYDROCYANIC-ACID GAS IN FUMIGATIONS. l 
In order to determine the actual effect of different proportions of 
sodium chlorid (which on being treated with strong sulphuric acid 
liberates hydrochloric acid) in cyanids, when used for fumigation 
work, on the amount of hydrocyanic-acid gas liberated, the following 
experiments were conducted. Samples were prepared from pure 
sodium cyanid and sodium chlorid containing various proportions of 
sodium chlorid from 9 to 66.66 per cent. 
Several experiments were also conducted, using pure sodium cyanid, 
containing 94 per cent of actual sodium cyanid (the remainder mainly 
moisture), for the purpose of determining the loss when using pure 
chemicals. These experiments were carried out as nearly as possible 
under the conditions actually obtaining in practical fumigation work, 
1 See also work on this subject by Newell, Georgia State Board of Entomology, Bulletin No. 15. 
