CHEMISTRY OF FUMIGATION. 99 



(HCX) 2 or H— N=€— H. 



C=N 

 The first product formed being imidoformylchlorid 



H— X=C— H, 

 CI 



which compound immediately combines with a second molecule of 



HCX thus 



HX XH 



H— X=C— H + HCX = ^C— C^ 



d H C1 



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 : 



hx. jm H 2 X\ .XH 



%c— cr +hci= ^c— cr 



b/ x ci b< I X C1 



HX. .XH H 2 X X /XH 2 



^C— C<f +2HC1= >C— C< 

 H/ X C1 *B< I | X C1 



CI CI 



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. 1 



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, 



i See also work on this subject by Newell, Georgia State Board of Entomology, Bulletin No. 15. 



