INSECTICIDES 479 



which is equivalent to prjictically 2 pounds of commercial lead 

 arsenate in the paste form. It may he made; up to 50 jj;allons 

 with water if a formula is Ix'iiij;- used which calls for 2 pounds 

 of commercial lead arsenatt^ to 5[) j>;allons, or if a stronger appli- 

 cation is desired add less water." 



Zinc Arsknite 



Arsenite of zinc, Zn (As()2)2, is a light fluffy |)owd(^r and con- 

 tains the equivalent of 40 j)er cent arsenious oxid. It has been 

 used extensively on the Pacific slojx^ as a substitute for arsenate 

 of lead. It kills insects somewhat more (juickly than the latter 

 poison and is fairly safe on apple foliage when us(m1 with Bor- 

 deaux or lime. When used in water or sw(^etened with molasses 

 or glucose it causes severe injury to grapti foliage, but may be 

 safely used with Bordeaux mixture. It is probable that foliage 

 injury by zinc arsenite ia^due to the solubility of this poison 

 in water containing a small quantity of carbonic acid ; the latter 

 is usually present on the leaves, being derived from the respira- 

 tion of the plant. One pound of zinc arsenite is equivalent in 

 effectiveness to about three pounds of arsenate of lead. 



Hellebore 



Hellebore is a light brown powder made from the roots of the 

 white hellebore plant {Veratrum album), one of the lily family. 

 It is applied both dry and in water. In the dry state, it is usu- 

 ally applied without dilution, although the addition of a little 

 flour will render it more adhesive. In water, 4 ounces of the 

 poison is mixed with 2 or 3 gallons, and an ounce of glue, or thin 

 flour paste, is sometimes added to make it adhere. A decoction 

 is made by using boiling water in the same proportions. Helhv 

 bore soon loses its strength, and a fresh article should always 

 be demanded. It is much less poisonous than the arsenicals, 



