
a Se eee 
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1go1] EFFECT OF HYDROCYANIC ACID GAS 243 
to the following chemical equation: 2KCN + H,SO, = 2HCN 
+K,SO,. Inthe later experiments bell jars were used having 
a capacity of approximately one third of a cubic foot each (fig. 
z). The bell jars were provided with ground glass stoppers, 
and were placed on ground glass plates, the edges being sealed 
with oil to prevent the escape of the gas. Having prepared the 
seeds in the manner desired, they were placed on the ground 
glass plate, and in a small beaker directly in the center of the 
plate was the dilute sulfuric acid, so that when the bell jar was 
placed in position the beaker containing the sulfuric acid was 
exactly below the glass stopper in the bell jar. The potassium 
cyanid was carefully weighed and wrapped in fine tissue paper. 
A piece of twine, just equal in length to the distance from the 
. lower surface of the glass stopper in the bell jar to the bottom 
of the beaker containing the sulfuric acid, was tied to a pack- 
age containing the desired weight of potassium cyanid, and the 
other end of the string was fastened by means of soft paraffin to 
the lower surface of the glass stopper of ‘the bell jar. When 
everything was ready to begin the experiment the package of 
potassium cyanid attached to the string was lowered through 
the opening in the top of the bell jar, and just at the instant 
when this package came into contact with the dilute sulfuric 
acid the ground glass stopper fell into place and thus hermeti- 
cally sealed the jar. By this means it was possible to keep 
the seeds for any required length of time in an atmosphere of 
hydrocyanic acid gas of desired strength. When the bell 
jars were opened, even after several months, the characteristic 
odor resembling peach kernels could be detected, showing that 
the gas had neither escaped nor been absorbed, although in at 
least some of the experiments a portion of the gas was probably 
absorbed, since it has a strong affinity for moisture. It should 
be borne in mind that both the potassium cyanid and the hydro- 
cyanic acid gas are deadly poisons and great care should be 
exercised in using them. Potassium cyanid is a white solid and 
is on the market in several forms. It should be purchased for 
use in the lump form usually known as 98 per cent. cyanid of 
