488 INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



ACID GENERATORS 



Acid generators are earthenware pots usually made in one-gallon, 

 two-gallon and three-gallon sizes, and with or without lids. The 

 lid has long been recognized as a valuable adjunct to a generator 

 by throwing the gas outward, thus preventing burnings directly 

 above the generator. It also prevents the sputtering over of the 

 acid due to the violent chemical reaction when the cyanide is added. 

 So far there appears to be no lid manufactured which is entirely 

 satisfactory, and the majority of the fumigators still use the open 

 generator. A suitable lid should be light and hinged, so as to admit 

 of easy emptying. 



The two-gallon generator is generally used because it more nearly 

 meets the requirements of large and small doses. Care should be 

 exercised not to fill a single pot more than one third full of acid 

 and water before the cyanide is added, as the contents may boil 

 over and much of it be wasted. For large doses use two or more 

 generators to a tree. To prevent unnecessary sputtering, especially 

 when open generators are used, the cyanide is often first placed in 

 small thin paper bags which are dropped directly into the diluted 

 sulphuric acid. 



MEASURING THE TENTS 



The air space of the tents is usually determined by a schedule based 

 upon the cubical contents of the tent, but in actual field operations 

 the present practice is to determine ounces by taking one per cent of 

 the product of the two dimensions of the tent in feet, thus for a tent 

 which is 20 feet over and 30 feet around we would have 20 X 30 = 600. 

 One per cent of this equals six ounces, which is very nearly Woglum's 

 schedule No. 1. The distance over is most easily ascertained by the 

 marked lines across the tent — the sum of the two figures nearest the 

 ground being taken. The distance around is often paced, but careful 

 fumigators use a tapeline, which is certainly the only procedure to be 

 recommended. The tapeline should be numbered in feet on both sides, 

 the numbering of each side being opposite so as to admit of the use 

 of either end without subtraction. A small, light snap is usually sewed 

 to each end, to be fastened to the ring at the top of a short iron pin 

 stuck in the ground to hold the loose end while the tape is carried 

 around the tent. A spring clothespin attached to one end of the tape 

 and snapped to a seam or fold of the tent is a very good way to secure 

 the tape while making measurements. 



DOSAGE SCHEDULES 



These schedules are printed on fairly stiff paper so that they may 

 be tacked upon a board for the use of the cyanide man. The figures 

 are black and large enough to be plainly seen by the light of a torch 

 or lantern on the darkest night. Half and quarter ounces are omitted 

 because of the difficulty in reading the small fractions at night and 

 because few scales are made to register these small amounts accu- 

 rately. All less than half ounces are placed in the lower figure, 

 while half ounces or over are placed in the next higher figure. A 



