18 
BULLETIN 1147, U. S. DEPARTMENT OF AGRICULTURE. 
The amount of arsenic made soluble was much larger when acid 
lead arsenate was combined with kerosene emulsion than when cal- 
cium arsenate was combined with it. The same amount of arsenic 
was rendered soluble in one day as in three days in the case of the 
acid lead arsenate. When calcium arsenate was used, 1.5 per cent 
more of the total arsenic was made soluble the third day than the 
first day. It is evident that the lead and the lime of the arsenates 
combined with the fatty acids to produce soaps, leaving the corre- 
sponding amounts of arsenic in a soluble condition. The results show 
that less decomposition occurred in the case of calcium arsenate 
mixed with kerosene emulsion than in the case of acid lead arsenate 
and kerosene emulsion. Both mixtures are chemically incompatible. 
ARSENATES AND FISH-OIL SOAP. 
Combinations of acid lead arsenate with fish-oil soap are sometimes 
made. Because of the large quantity of calcium arsenate now being 
manufactured, it seemed advisable to test combinations of calcium 
arsenate and of acid lead arsenate with fish-oil soap in order to deter- 
mine how much arsenic might be made soluble. 
Fish-oil soap solutions of two strengths, 1 and 2 pounds of soap 
per 50 gallons, were prepared. The fish-oil soap was the same kind 
as that used in making the kerosene emulsion. A series of 300 cubic 
centimeter flasks were filled with the soap solution. No arsenical 
was added to some of the flasks which were used as controls, but 0.8 
gram of acid lead arsenate (sample 39) or 0.667 gram of calcium 
arsenate (sample 57) was added to the others. A one-day period 
was taken for agitating the solutions, because the results with kero- 
sene emulsion showed that in one day the reactions were practically 
complete for the lead arsenate and much retarded in the case of the 
calcium arsenate. 
Table 8. — Arsenic rendered soluble on combining lead or calcium arsenates with fish-oil 
soap. 
Sample 
No. 
Material analyzed. 
Arsenic 
(As)present 
in sample 
taken. 
Arsenic (As) rendered 
soluble after standing 
for 1 day. 
sr 
Calcium arsenate * 
Grams. 
0. 1753 
.1717 
.1753 
.1717 
.1753 
.1717 
Grams. 
0.0003 
.0032 
.0503 
.1475 
.0667 
.1703 
Per cent. 
0.17 
39 
Acid lead arsenate 2 
Calcium arsenate plus fish-oil soap (1 pound to 50 gallons) . 
Acid lead arsenate plus fish-oil soap ( 1 pound to 50 gallons) . . 
Calcium arsenate plus fish-oil soap (2 pounds to 50 gallons) . . 
Acid lead arsenate plus fish-oil soap (2 pounds to 50 gallons) . 
1.86 
28.69 
85.90 
38.05 
99.18 
1 Calcium arsenate at the rate of 0.93 pound per 50 gallons. 
2 Lead arsenate at the rate of 1.11 pounds per 50 gallons. 
The results obtained (Table 8) follow the trend of the results 
secured with kerosene emulsion (Table 7) in that they show that 
more arsenic was rendered soluble when acid lead arsenate was used 
than when calcium arsenate was used. They also show that the 
greater the quantity of fish-oil soap used the larger the amount of 
soluble arsenic formed. All of the arsenic was made soluble when 
acid lead arsenate was mixed with the soap at the rate of 2 pounds 
per 50 gallons. The lead soaps are more readily formed than the 
