152 Princtples of Plant Culture. 
286. White Arsenic (arsenious acid) is slightly solu- 
ble in water, and hence is dangerous to foliage unless used 
with care. If applied immediately after its addition to the 
water, it may be safely used upon the foliage of the apple, 
plum and cherry at the rate of one pound to fifty gallons, 
but constant stirring is required to keep it in suspension. 
287. London Purple (arsenite of lime, with certain 
impurities) often contains soluble arsenic, and, like white 
arsenic, must be used with caution. It may be safely 
applied to many plants at the rate of one pound to two 
hundred gallons of water, if put on immediately after its 
addition to the liquid, but for the peach it should receive 
greater dilution. London purple is considerably cheaper in 
the market than Paris green. 
The addition of fresh milk of lime to water to which 
white arsenic or London purple has been added largely pre- 
vents their tendency to injure foliage. 
Both Paris green and London purple, when perfectly 
mixed with 150 parts, by weight, of land paster, or an equal 
bulk of any other cheap non-poisonous powder, are effectual 
in destroying the potato beetle and many other leaf-eating 
insects (307). 
288. Compounds of Arsenic are Deadly Poisons and 
should always be handled with the greatest care. 
289. Hellebore (hel’-le-bore) Powder, i. e., the ground 
root of white hellebore,* is a far less virulent poison than 
the arsenic compounds. It is therefore useful for destroy- 
ing a class of insects against which a deadly poison cannot 
wisely be used, as the imported currant worm,t and the 
cabbage caterpillar.t 
* Veratum album. ‘+ Nematus ribesii. { Pieris rape. 
