CHEMISTRY OF FUMIGATION. 
103 
Experiments on commercial cyanids. 
Ex- 
Serial 
No. 
Material. 
Equiv- 
alent of 
HCN in 
sample. 
Sodium 
chlorid 
in sam- 
ple. 
HCN 
evolved. 
HCN 
remain- 
ing in 
residue. 
HCN 
decom- 
posed 
(by dif- 
fer- 
ence). 
Per cent of total HCN— 
peri- 
ment 
No. 
Evolved. 
In resi- 
due. 
Decom- 
posed. 
11 
12 
13 
6523 
6524 
6525 
6526 
6527 
6528 
6529 
Potassium cyanid . . . 
Sodium cj-anid 
do 
Per ct. 
40.42 
41.78 
51.22 
41.45 
39. 96 
39.28 
41.02 
Per ct. 
0.40 
14.20 
.57 
5.82 
.60 
.77 
6.15 
Per ct. 
37.95 
26.22 
48.31 
36.93 
37. 51 
36.71 
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 
93.88 
62.76 
94.32 
89.10 
93.87 
93.46 
85.75 
3.03 
3.17 
5.09 
4.92 
4.27 
3.57 
4.49 
3.09 
34.07 
.59 
14 
.do. 1 ... 
5.98 
15 
16 
17 
Potassium cyanid 
do 
" Sodium cyanid " l . . 
1.86 
2.97 
9.76 
i 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 No. 6525 as from 
No. 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 results. 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. 
Equiva- 
lent of 
HCN in 
sample. 
Sodium 
nitrate 
in sam- 
ple. 
HCN 
evolved. 
HCN re- 
maining 
in resi- 
due. 
HCN de- 
com- 
posed (by 
differ- 
ence). 
Per cent of total HCN— 
Experiment No. 
Evolved. 
In resi- 
due. 
Decom- 
posed. 
18... 
Per cent. 
47.16 
43.18 
25.91 
17.27 
Per cent. 
9 
16f 
50 
66§ 
Per cent. 
39.92 
37.73 
21.22 
13.12 
Per cent, 
1.26 
1.32 
1.14 
.79 
Per cent. 
5.98 
4.13 
3.65 
3.36 
84.66 
87.39 
81.51 
75.95 
2.67 
3.05 
4.40 
4.56 
12.67 
19 
9 56 
20... 
14 09 
21 
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 chlorid s. The nitrogen in the decomposed cyanid is in 
this case also converted into ammonia. 
67330°— Bull. 90—12 8 
