46 HYDROCYAXIC-ACID GAS FUMIGATION IN CALIFORNIA. 



(avoirdupois) of potassium cyanid were employed in each experi- 

 ment, and 3. 6, 9, 12, 15, IS, 21, and 24 ounces, respectively, of 

 water were used in the different experiments. 



From this chart it is evident that with the grades of acid and 

 cyanid mentioned the largest amount of gas is available from 2 parts 

 of water. As the proportion of water is increased above 2 parts the 

 available gas is decreased, until with S parts of water we obtam only 

 about 43 per cent of gas. or less than one-half as much as with 2 

 parts. In other words. 1 ounce of cyanid and 1 ounce of acid in 

 combination with 2 ounces of water will produce much more avail- 

 able gas than 2 ounces of cyanid and 2 ounces of acid with 16 ounces 

 of water. 



The cause for the smaller amount of gas with 1 part of water has 

 been explained on page 44. One of the principal reasons for the 

 decrease of the amount of gas as we go above 2 parts of water is that 

 the temperature of the acid-water mixture decreases as the pro- 

 portion of water increases. "With dosages of 5 ounces of cyanid the 

 temperature was foimd to be 190° F. where two parts of water were 

 used, but only 125° F. with S parts of water. The hotter the acid- 

 water mixture the quicker and more violent the reaction with the 

 cyanid will be. Secondly, hydrocyanic-acid gas is very soluble in 

 water. As the cyanid is immersed during the reaction, the gas has 

 to rise through the liquid in order to escape. Less gas will be 

 absorbed by rapid evolution through a small amotmt of water than 

 by slower rise through a large amount. ■ 



The proportion of water used by different fumigators under the old 

 system has varied all the way from 2 to S parts, some men even 

 varying widely in their individual work. In brief, the method fol- 

 lowed by the "generator" man in dosing has been that on comino: to 

 a tree he first looks at his can of cyanid for that tree and then makes 

 a guess as to how many ounces it contains. If he is using 2 parts of 

 water he will use twice the amount that he thinks there is cyanid in 

 the can: if S parts, then 8 times the amount of cyanid he thinks 

 there is in the can. A very few outfits have measured the water in 

 graduated beakers: the majority of receptacles used have varied all 

 the way from half-pint dippers to quart dippers, quart pitchers, or 

 even old tin cans. Think of measuring with accuracy the amount of 

 water for a tree requiring 4 ounces of cyanid with a quart pitcher! 

 The writer ha- frequently seen fumigators. hi measuring the water 

 for a tree, first measure out what they thought to be the proper 

 amount, then hesitate as to whether it was enough, and finally dip 

 out a second or even a third portion. Those second and third dips 

 meant less available gas. and the common multifold guessing in the 

 measure of water under the old system has been directly responsible 

 for irregular results. 



