CHEMISTRY OF FUMIGATION. 

 Experiments on commercial cyanids. 



103 



Ex- 





peri- 



Serial 



ment 



No. 



No. 





11 



6-523 



12 



(••.524 



13 



6525 



14 



6526 



15 



6527 



16 



652S 



17 



'529 



Material. 



HCX ' Per cent of total HCX— 



Equiv- Sodium 

 alentof chlorid 

 HCX in in sam- 

 sample. pie. 



HCX 

 evolved. 



Potassium cyanid 

 Sodium c\anid 



do..: 



do. 1 



Potassium evanid. 

 .do. 



• • Sodium eyanid " l 



Per ct. 

 40.42 

 41.78 

 51.22 

 41.45 

 39.96 

 39.28 



Per ct. 



0.40 



14.20 



.57 



5.82 



.60 



Per ct. 

 37.95 

 26.22 

 48.31 

 36. 93 

 37. 51 

 36.71 



HCX decom- 

 remain- posed 



ing in (by dif- 

 residue. fer- 

 ence). 



41.02 6.15 35.17 



Per ct. 

 1.22 

 1.32 

 2.31 

 2.04 

 1.71 

 1.40 

 1.84 



Per ct. 



1.25 



14.24 



.30 



2.48 



.74 



1.17 



4.01 



Evolved, 



93.88 

 62.76 

 94.32 

 89.10 

 93.87 

 93. 46 

 85.75 



In resi- 

 due. 



Decom- 

 posed. 



3.03 

 3.17 

 5.09 

 4.92 

 4.27 

 3.57 

 4.49 



3.09 

 34.07 

 .59 

 5.98 

 1.86 

 2.97 

 9.76 



1 A mixture of potassium and sodium cyanids and sodium chlorid. 



This work shows the great variation in the yield of hydrocyanic 

 acid obtained when using samples as they appear upon the market, 

 nearly twice as much being obtained from sample Xo. 6525 as from 

 Xo. 6524. In view of such varying results as these it is not surprising 

 that fumigation has so often proved a failure. 



EFFECT OF THE PRESENCE OF SODIUM NITRATE IN CYANIDS ON 

 THE YIELD OF HYDROCYANIC-ACID GAS. 



Experiments carried out in the same way, using the same pure 

 sodium cyanid, to which varying proportions of sodium nitrate had 

 been added, gave results similar to those in which sodium chlorid was 

 present. This fact is of no practical utility in so far as fumigation 

 work is concerned, as cyanids do not contain nitrates as an impurity. 

 Commercial sulphuric acid may contain traces of nitric acid, but 

 the amount is so minute that it would have no appreciable effect on 

 the result^. Aside from this, the action of such an energetic oxidizing 

 agent as nitric acid, in the presence of strong sulphuric acid, upon 

 cyanids would be attended with some danger. The results of these 

 experiments are given in the following table: 



Effect of nitrates on the yield of hydrocyanic-acid gas. 



Experiment Xo. 



18 

 19 



30 



21 



Equiva- Sodium 



lent of nitrate 



HCX in j in sam- 



sample. pie. 



HCX 

 evolved. 



Per cent. 



Per cent. 



47.16 



9 



43.18 



16§ 



25.91 



50 



17.27 



66§ 



Per cent. 

 39.92 

 37.73 

 21.22 

 13.12 



HCX re- 

 maining 

 in resi- 

 due. 



HCX de- 

 com- 

 posed (by 

 differ- 

 ence). 



Per cent of total HCX- 



Per cent. 

 1.26 

 1.32 

 1.14 



Per cent. 

 5.98 

 4.13 

 3.65 

 3.36 



Evolved. 



84.66 

 87.39 

 81.51 

 75.95 



In resi- 

 due. 



Decom- 

 posed. 



2.67 

 3.05 

 4.40 

 4.56 



12.67 



9.56 



14.09 



19.49 



The presence of nitrates exerts a very decided decomposing action 

 on the hydrocyanic acid, but this action is much less than that pro- 

 duced by chlorids. The nitrogen in the decomposed cyanid is in 

 this case also converted into ammonia. 



