22 
BULLETIN 1147, IT. S. DEPARTMENT OE AGRICULTURE. 
Table 11. — Arsenic on potato leaves sprayed with arsenicals with and without the addition 
of lime} 
Sample 
No. 
Material used. 
Total 
arsenic 
oxid 
(As 2 5 ) 
in dry 
arsenical. 
Arsenical 
used 
per 10 
gallons. 
Arsenic 
(As) 
on dry 
leaves. 
24 
24A 
40 
40A 
23 
86 
87 
87A 
87B 
88 
8SA 
88B 
Calcium arsenate 
Sample 24 plus lime (2 ounces) 
Acid lead arsenate 
Sample 40 plus lime ^2 ounces) 
Zinc arsenite 
Calcium meta-arsenate 
Calcium arsenate 
Sample 87 plus lime (2 ounces) 
Sample 87 plus lime (4 ounces) 
Calcium arsenate 
Sample 88 plus lime (2 ounces) 
Sample 88 plus lime (4 ounces) 
Per cent. 
49.40 
49.40 
32.76 
32.76 
2 41. 49 
79.60 
55.00 
55.00 
55.00 
42.80 
42.80 
42.80 
Ounces. 
2 
2 
n 
f 
2 
2 
% 
2§ 
2i 
Parts per 
million. 
240 
340 
530 
580 
540 
830 
290 
270 
290 
360 
1 Equal percentages of AS2O3 and AS2O5 were used for all the sprays. 
2 AS2O3. 
During the season of 1920 potato plants were sprayed at Arlington, 
Va., using (a) dry acid lead arsenate, (b) dry " suspender" 7 acid lead 
arsenate, (c) zinc arsenite, and (d) Paris green. The sprays were 
made to contain the same percentage of arsenious or arsenic oxid and 
were applied four times during the season, using a power sprayer. 
Nine duplicate sets of 50 leaves each were collected on the same days 
throughout the season from each plot of the various sprayed vines. 
These leaves (900 in all from each plot receiving a different spray) 
were analyzed for arsenic, with the following average results, ex- 
pressed as parts of arsenic per million of dried potato leaves: Paris 
green, 155; " suspender" acid lead arsenate, 195; zinc arsenite, 203; 
and acid lead arsenate, 210. 
The physical properties of arsenicals have been studied to some 
extent since the time they were first prepared, but no complete study 
has been reported. This may be due in part' to the difficulties 
encountered in measuring those physical properties which contribute 
toward making a satisfactory product for dusting or spraying. 
Wilson (53) in 1919 gave data on the burning, suspensibility, and 
adhesiveness of Paris green, zinc arsenite, acid and basic lead arse- 
nates, and calcium arsenate. 
A series of tests was performed, using commercial powdered arsen- 
icals (Table 12), to obtain comparative data on the apparent density 
and suspensibility of these products. The apparent density of a 
powder here described is based on the number of grams occupying 
a volume of 1,000 cubic centimeters and the suspensibility on the 
volumetric readings of 30 grams of powder which had settled after 
having been shaken for one minute with approximately 500 cubic 
centimeters of water and having stood for 10 and for 60 minutes. 
7 "Suspender" lead arsenate is a trade name applied to a powdered lead arsenate containing some added 
organic substance for the purpose of keeping the arsenate in suspension when mixed with water. 
