ARSENATE OF LEAD 67 
lead is a compound of arsenic, but is a less violent poison than Paris 
green. The standard requirements for the paste call for at least 123 
per cent arsenic oxid, not over ? per cent soluble arsenic, and not 
over 50 per cent water. 
To apply as a spray, the paste may be mixed with water, with Bor- 
deaux mixture, or with lime-sulphur solution. In either case the 
strength to employ is from 3 to 10 pounds of the paste in 50 
gallons of water, or of Bordeaux mixture, or of lime-sulphur solution. 
If the dry lead arsenate is used in making up a spray, it is advan- 
tageous to employ the finely powdered form made by the “ electro ”’ 
process. The proportions will be from 1 to 4 pounds of the powder to 
50 gallons. 
Either the paste or the powder should first be mixed with a little 
water, so as to get it into a thin paste. It is entirely unnecessary to 
add lime. 
Owing to the fact that arsenate of lead is not as violent a poison as 
Paris green, it is necessary to use heavier doses for larger or resistant 
insects, as indicated in the formula given above. 
Powdered arsenate of lead, applied dry, is developing a special field 
of usefulness and promises to become a valuable form of insecticide 
application. Paris green has been used in this way for many years, 
especially on some truck and field crops in the South; but it is rather 
likely to burn the foliage and is easily washed off by rains. Powdered 
lead arsenate, especially the amorphous form made by the so-called 
“ electro’ process, rarely will burn the plants, and if applied after a 
shower or when the dew is on the leaves, it sticks tightly. 
On most truck crops or field crops it has important advantages over 
liquid applications. The apparatus for applying it is light and inex- 
pensive; large areas can be covered easily and rapidly; the need of 
drawing a heavy cart through the field is obviated; and if a good pow- 
der gun is used, the material can be forced in large quantities into the 
places where it will do the most good. It is not suitable for orchard 
work in general, or for work of such character as vineyard spraying. 
Advantages of lead arsenate are the facts that it will not usually 
burn foliage, that it stays in suspension in the spray mixture fairly 
