INSECT CONTROL 329 



Formerly London purple, arsenite of lime, and other 

 arsenicals were much used, but the above are practically 

 the only arsenicals now having a general use. 



Arsenate of Lime. Recently the U. S. Bureau of Ento- 

 mology has reported favorably upon a home-made sub- 

 stitute for arsenate of lead, made of lime and sodium arsen- 

 ate, according to the following formula: 



"Stone Lime (90% CaO) 55 pounds 



Sodium arsenate, fused (dry pow- 

 dered) 65% As 2 5 100 pounds 



Water 26 gallons 



"Place the stone lime in a wooden container and add 

 a small amount of water, just enough to start slaking. When 

 slaking is well under way, pour in the sodium arsenate, 

 which should first have been dissolved in hot water. Keep 

 stirring until the lime has thoroughly slaked. Sufficient 

 water should be added from time to time to prevent burning. 

 The resulting arsenate of calcium should contain about 18 

 per cent of arsenic oxid, or slightly more than in average 

 arsenate of lead paste. In making this compound, one 

 should know approximately the calcium oxid and arsenic 

 oxid of the materials employed and vary the formula ac- 

 cordingly. 



" In the experience of the Bureau of Entomology, arsenate 

 of lime, made according to the above formula, compares fa- 

 vorably with arsenate of lead in killing effect, and has not 

 caused injury to foliage of plants treated. This new in- 

 secticide, however, must still be regarded in its experimental 

 stage. Its cheapness over arsenate of lead is its principal 

 recommendation . ' ' 



Poisoned Bran Mash. For combating grasshoppers and 

 cutworms arsenic is often employed mixed in a bran mash. 



