24 
Bulletin 71. 
arsenites, consequently it is necessary to use it in stronger mixtures. 
To prepare arsenate of lead, dissolve in water arsenate of soda 
and acetate of lead (white sugar of lead) in the proportion of three 
pounds of the former to seven pounds of the latter. Then use not 
less than two or three pounds of the combined chemicals to each 
hundred gallons of water. Three or four times this strength will do 
no harm to foliage. 
6. ARSENITE OF LIME. 
White arsenic and lime may be made to combine, forming an 
arsenite of lime that is practically insoluble in water. The poison 
may be prepared in either of two ways. What is known as the 
Kedzie formula is as follows: 
“Boil two pounds of white arsenic and eight pounds of sal- 
soda for fifteen minutes in two gallons of water. Put into a jug 
and label ‘ poison ,’ and lock it up. When ready to spray, slake 
two pounds of lime and stir it into forty gallons of water, adding 
a pint of the mixture from the jug.” 
The other method is to boil together arsenic, lime and water 
for a full half hour in the following proportions: 
White arsenic.1 pound 
Lump lime.2 pounds 
Water . 3 gallons 
Then dilute to 200 gallons of water before applying to foliage. 
These preparations have become very popular in the past two 
years and deservedly so. White arsenic is cheap and consequently 
is in very little danger of adulteration, so: hat one is almost certain 
of the strength of his mixture when using this poison. Care must 
be taken, however, to use fresh, unslaked lime of good quality. 
Before being diluted for use, the mixture should be passed 
through a coarse cloth or sieve, to take out the lumps that would 
otherwise clog the spraying nozzle. 
7. LONDON PURPLE. 
London purple is a by-product in the manufacture of aniline 
dyes and has for its active principle arsenite of lime. It also con¬ 
tains some free arsenic, lime, coloring matter and other impurities. 
The amount of arsenic present is subject to considerable variation, 
but will usually range between 40 and 55 per cent. As there is 
often considerable soluble arsenic present, it is always best to use a 
pound or two of freshly slaked lime with every pound of the poison 
if used in water. 
This poison is finely divided and remains in suspension in 
water much longer than does Paris green, and it usually sells at 
about two-thirds the price of that poison. It seems to be going into 
disfavor because of its variable composition and the danger of its 
