New YorkK AGRICULTURAL EXPERIMENT STATION. 305 
cases the latter interfered with rapid emptying and refilling of 
generators. Where the chemicals were used in the proportion 
of 1-1-8, the action was entirely too ‘slow on the ordinary size 
of broken cyanide. In some instances it was not even complete 
in the period allowed for fumigation of a tree. 
The use of equal amounts of acid and water, even though 
greater than the amount of potassium cyanide, did not give 
increased chemical action. — 
The use of an excess of acid and three times as much water 
did not materially decrease the rate of chemical action. 
In general the table shows that a slight excess of acid and 
two to four times as much water gave fairly good results, but 
in cases where powdered potassium cyanide was used the chem- 
ical action was violent enough to throw the contents out of the 
generator. 
CONCLUSION. 
It should be observed that the smaller the pieces of potassium 
cyanide the less time required for chemical action, no matter 
what ratio of acid and water was used. By the use of one and 
a half times as much acid and three times as much water as of 
potassium cyanide, by volume, the action was nearly as rapid 
with large pieces as with small pieces when used with less acid 
and water. 
Where large quantities of potassium cyanide are broken fine 
there is a waste not only by decomposition on exposure to the 
air but also by its being thrown out of the generator when 
chemical action begins. Having it broken to a definite size, as 
some have recommended means an additional expense of 2 cents 
per lb. on wholesale price, but by using the finely broken 
potassium cyanide and an equal amount of sulphuric acid by 
volume the total cost per charge of chemicals is the same as 
where ordinary broken cyanide is used with one and a half times 
as much sulphuric acid by volume. Hence the principal gain 
in using the ordinary broken potassium cyanide of the trade and 
a larger amount of sulphuric acid is prevention of waste; at the 
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