﻿ABSORPTION OF HYDROCYANIC ACID. 5 



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 dosed 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 fumfgatorium 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 \\ 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 



Product . 



Sodium cyanide. 



NAP Vac 



Tem- 

 pera- 

 ture. 



Rela- 

 tive 



Period 

 after 



Hydrocyanic acid in — 



humid- fumi- 

 ity. gation. 



Whole 

 fruit. 



Rind. 



Flesh. 



Apples: 

 Ripe . . . 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 



Oz. per 



100 

 cu.ft. 



Oz.per 

 100 



cu.ft. 

 4 

 4 

 2 

 2 



°F. 

 64 

 64 

 75 

 75 

 72 

 72 

 74 

 74 



• Parts 

 1 per 

 Days, million. 



Parts 

 per 



million 



Parts 



per 

 million. 



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. 



