INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



487 



gation methods. Such a machine admits of very rapid work and 

 almost entirely eliminates the danger of burning the tents with acid. 



Acid Container. — For ordinary work a three, five or ten gallon 

 earthenware jar is sufficient, A lead lid for the top and a three 

 fourths inch iron pipe inserted through a hole in the side near the 

 bottom with a piece of pure rubber tubing six inches long and closed by 

 an acid clamp is a cheap and practical device. Lead-lined tanks are 

 more durable, but also much more expensive. 



Water Tank. — As there is two or three times as much water used 

 as acid the water tank must necessarily be larger. For a hand cart 

 a pickle keg is excellent, while a twenty-five or fifty-gallon barrel 

 may be necessary for a large wagon. An extension pipe and faucet 

 furnish the outlet, which should be near that of the acid tank. 



Graduates. — The quantity of acid and water used depends entirely 

 upon the amount of cyanide required for a dose. For every ounce of 

 potassium cyanide one fluid ounce of sulphuric acid and three fluid 

 ounces of water are used, while for sodium cvanide one and a half 



Fig. 486. — A specially constructed chemical wagon. (Photo by H. S. Fawcett) 



fluid ounces of sulphuric acid and two fluid ounces of water are 

 used. As this is a fixed ratio in each case, graduates have been 

 made to measure out the exact amount of the liquid required in the 

 terms of the number of ounces of cyanide; for instance, if it required 

 twelve ounces of sodium cyanide for a dose, the acid graduate is so 

 scaled that it would be filled to the twelve-ounce line, which would 

 mean eighteen fluid ounces, and the water graduate to the twelve- 

 ounce line, which would be twenty-four fluid ounces. Such ;i scheme 

 makes it unnecessary to make mental calculations and thus avoids 

 mistakes. 



