5 
Arsenite of lime.—This is normally a home-made preparation, and 
there is no reason for its not being employed wherever one is willing 
‘to take the trouble to compound it carefully. Its preparation, de- 
scribed below, following substantially the Kedzie formula, is simple 
enough: 
PERE NOU ete re ee ee pounds... 1 
eS gS co ae ie 3 ES SE pA ee ee G0e2=- 
MNCERREIO 22 45 Se ee ee Oe oe ED ee eee ee ee Dane Ee | eee gallons__ 1 
Place the above ingredients in an iron vessel, which is to be kept 
exclusively for this purpose, and boil for twenty minutes or until 
dissolved. ‘To 40 or 50 gallons of water a pint of this stock solution 
and 3 to 4 pounds of freshly slaked lime are added. This excess 
of lime not only takes up any free arsenic, but by its distribution on 
the foliage enables one to determine how well the spraying has been 
done. This formula has been thoroughly tested and used now for 
many years, and is fully as efficient as any other arsenical and far 
cheaper. Chemically it is arsenite of lime. The soda is used to 
hasten the process and to insure the combination of all the arsenic 
with the lime. The greatest care should be exercised in preparing 
the stock mixture, and afterwards it should be plainly labeled to pre- 
vent its being mistaken for some other substance. The only objec- 
tion to its use is the necessity of handling the poisons in its home 
preparation. 
London purple.—London purple is a waste product in the manufac- 
ture of aniline dyes and contains a number of substances, the chief 
of which are white arsenic and lime. It is not so effective as the 
copper arsenites, and contains a much larger percentage of soluble 
arsenic, and is very apt to scald foliage unless very carefully mixed 
with fresh stone lime. It comes as a very fine powder, and is easily 
kept in suspension. It costs about 10 cents a pound. If employed, 
the lime should always be added. 
Arsenate of lead.—Arsenate of lead may be prepared at home by 
combining approximately 3 parts of the crystallized arsenate of soda 
with 7 parts of crystallized acetate of lead (sugar of lead) in water. 
This gives a slight excess of acetate of lead. Each of the ingredients 
should be dissolved separately in water in wooden vessels, and the 
two solutions poured together into the spray tank filled with water. 
The white, flocculent precipitate of arsenate of lead which im- 
mediately results is extremely fine and remains in suspension much 
longer than any other arsenical. Furthermore, prepared in this way 
and diluted at once, there is secured a mixture that is chemically su- 
perior to the combined product sold in paste form and that remains in 

@Two pounds only of the anhydrous sal soda are necessary. 
73159—Bul. 127—09—_2 
