ABSORPTION OF HYDROCYANIC ACID. 
water in the proportion of 2\ : 1 : 1 . That is, for every 2\ fluid ounces of 
cyanide solution, 6 1 fluid ounce of acid and 1 fluid ounce of water are 
used. The procedure is as follows: The material to be fumigated 
is placed in the fumigation chamber, in this case a horizontal iron 
retort with a capacity of 100 cubic feet, and the door is closed and 
clamped. The air is exhausted until the gauge registers 26 inches. 
At this stage the gas is generated by introducing into the generator 
the chemicals in the following order: Water, acid, cyanide in solu- 
tion. The valve separating the generator from the fumigation cham- 
ber is opened, and the cyanide solution is allowed to flow slowly into 
the diluted acid in the generator. When all the cyanide solution has 
entered, the outside valve of the generator is opened, and the air is 
allowed to wash all of the gas over into the fumigation chamber. 
After washing for 5 minutes the vacuum in the iumigatorium is 
completely broken. The material is exposed to the gas for a period 
of time equal to 1 hour from the time the cyanide solution started 
to flow into the generator. To remove the gas-air mixture at the end 
of the exposure period, the fumigation chamber should be pumped 
to a vacuum of 25 inches. The valves of the chamber are then 
opened and the vacuum is broken. The chamber is opened and the 
material to be analyzed is removed. 
Commercial 96-98 per cent sodium cyanide, usually at the rate of 
4 ounces per hundred cubic feet of fumigated space, was used in this 
work, and the gas formed from it when treated with commercial 93 
per cent sulphuric acid was allowed to remain in contact with the 
product for the time indicated. Even this dosage is higher than that 
now used in practice, usually 1} to 2 ounces of sodium cyanide per 
hundred cubic feet. 
The temperature and humidity were accurately determined and 
recorded in each case. 
Part of the material was analyzed immediately after fumigation, 
and part of it was stored in the refrigerator for 24 hours before being 
analyzed. Material which is usually pared before consumption was 
pared and separate analyses were made on the rind and flesh. 
Hydrocyanic acid was determined, after distillation with tartaric 
acid, by the method of Viehoever and Johns (23). The results of 
these experiments are shown in Table 2. 
Table 2. — Hydrocyanic acid in fruits and vegetables after fumigation. 1 
Sodium cyanide. 
Tem- 
pera- 
ture. 
Rela- 
tive 
humid- 
ity. 
Period 
after 
fumi- 
gation. 
Hydrocyanic acid in- 
Product. 
NAP 
Vac. 
Whole 
fruit. 
Rind. 
Flesh. 
Apples: 
Oz. per 
100 
cu.ft. 
Oz. per 
100 
cu.ft. 
4 
4 
2 
2 
"*,'4* 
°F. 
64 
64 
75 
75 
72 
72 
74 
43 
43 
51 
51 
33 
33 
23 
23 
Days. 
1 
2 



1 

1 
Parts 
per 
million. 
23 
5 
42 
36 
Parts 
per 
million . 
Parts 
per 
million. 
Do . 
Do... 
Do. 
Do 
4 
4 
7 
6 
97 
16 
6 
Do 
2 
Do 
42 
Do 
4 74 
5 
1 All samples were exposed to the fumes for 1 hour, with the exception of the first pineapple sample, which 
was exposed for 70 minutes. 
2 Sample cut and allowed to stand overnight before analysis. 
< This is made by dissolving sodium cyanide in water at the rate of 200 pounds to 50 gallons. 
