CHEMISTRY OF FUMIGATION. 95 



Experiments to determine the best proportion of chemicals to be used. 



Experiment No. 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



15 



1(3 



17 



18 



Amount of chemicals used. 



HCXre- j 



Sodium 



cyanid 



(NaCN). 



Sulphuric 



acid 

 (H 2 S0<). 



Water 

 (H 2 0). 



residue 

 (per cent 

 of total). 



Oz., avoir. 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 

 3 



Fluid oz. 

 3 

 3 

 3 

 3 

 3 

 4 

 4 

 4 

 4 

 4 

 5 

 5 

 5 

 5. 

 6 

 6 

 6 

 6 



Fluid oz. 



3 



4 



5 



6 



9 



4 



6 



8 



10 



12 



5 



7| 



10 



15 



6 



8 



10 



12 



12.94 

 17.58 

 10.19 

 7.48 

 9.18 

 1.44 

 2.49 

 4.36 

 7.53 

 8.14 

 1.40 

 4.04 

 5.92 

 9.91 

 1.22 

 2.74 

 3.46 

 5.00 



HCX ex- 

 pelled (by 

 difference). 



Per cent. 

 87.06 

 82.42 

 89.81 

 92.52 

 90.82 

 98.56 

 97.51 

 95.64 

 92.47 

 91.86 

 98.60 

 95.96 

 94.08 

 90.09 

 98.78 

 97.26 

 96.54 

 95.00 



The following experiments were then made on samples of sodium 

 cyanid of varying composition: No. 6524 contained 75.78 per cent of 

 sodium cyanid and 14.20 per cent of sodium chlorid; No. 6525 con- 

 tained 92.92 of sodium cyanid; and No. 6526 contained 75.18 per 

 cent calculated as sodium cyanid and 5.82 per cent of sodium chlorid. 



Experiments with different samples of sodium cyanid. 



Experiment No. 



Amount of chemicals used. 



HCN remaining in residue 

 (per cent of total). 



Sodium 

 cyanid. 



SU a?id UriC Water " 



No. 6524. ! No. 6525. 



No. 6526.1 



19 



Oz.,avoir. 

 3 

 3 

 3 

 3 

 3 

 3 

 3 



Fluid oz. Fluid oz. 

 3 3 

 3 6 



10.74 



7.68 



7.27 



.62 



12.22 

 8.16 

 9.32 

 3.16 



8.53 



20 



7.22 



21 



3 

 4 

 4 

 5 

 6 



9 

 4 

 6 

 5 

 6 





22 



.80 



23 



1.65 ! 



.39 ; 1.73 

 .24 



3.21 



24 



.53 



25 



.58 















1 A mixture of sodium cyanid, potassium cyanid, and sodium chlorid. 



The acid acts very energetically on the sodium cyanid, and by 

 comparing the results with those obtained in previous work with 

 potassium cyanid it is shown that less hydrocyanic acid remains in 

 the residue when using sodium cyanid. It may be stated here that 

 the very low results obtained with the impure cyanids Nos. 6524 and 

 6526 are due to the decomposing action of hydrochloric acid, liberated 

 from the sodium chlorid, on the hydrocyanic acid. When equal 

 quantities of cyanid, acid, and water were used, there was not enough 

 acid present to cause complete decomposition of the cyanid — decom- 

 posed lumps of which always remained in the residue — nor was 



