ARSENIC ALS. 
15 
Table 6. 
-Composition of lime-sulphur solution and of the filtrates from mixtures of 
lead arsenate or calcium arsenate and lime-sulphur solution. 
After 
having 
been 
shaken 
for— 
Composition (grams per 500 cubic centimeters). 
Material analyzed. 
Total 
lime 
(CaO). 
Total 
sulphur 
(S). 
Sulphid 
sulphur 
(S). 
Thio- 
sulphate 
sulphur 
(S). 
Sulphate 
sulphur 
(S). 
Arsenic 
oxid 
(As 2 5 ). 
Series 1: 
Lime-sulphur solution 
Filtrates from mixtures of 
flhour 
\91 hours... 
fl hour 
J 19 hours... 
1.9680 
2. 0520 
1.8050 
4.9430 
4.9290 
4.4770 
4. 2670 
4.2560 
4.2790 
5.2500 
5.2500 
5.2000 
5.1000 
5.0500 
5.1000 
4.5190 
4.5060 
4. 1620 
4.0450 
3. 9080 
3. 7110 
4.7800 
4.7500 
4.7000 
4.7500 
4.6800 
4.7000 
0. 1960 
.2030 
.2020 
.1990 
.1980 
.1970 
.3200 
.3200 
.3300 
.3200 
.3300 
.3600 
0.0035 
.0069 
.0029 
.0055 
.0036 
.0076 
.0089 
.0099 
.0077 
.0089 
.0087 
.0108 
0.0002 
.0002 
.0270 
.0205 
lead arsenate and lime- 
sulphur solution 
Series 2: 
Lime-sulphur solution 
Filtrates from mixtures of 
calcium arsenate and 
lime-sulphur solution. . . 
1 43 hours... 
.0199 
191 hours... 
flhour 
{21 hours... 
[5 days 
flhour 
{21 hours... 
(5 days 
1.8030 
1.9800 
1.9900 
2.0400 
2.0400 
2.0600 
1.9600 
.0200 
.0002 
.0002 
.0003 
.0008 
.0005 
.0010 
Using the analytical data on the lime-sulphur solution as controls, 
the analytical results on filtrates from a mixture of lead arsenate and 
lime-sulphur solution show the following: (a) The total lime in 
solution was reduced 10 per cent after having been shaken for either 
1 hour or 91 hours; (b) the total sulphur in solution was reduced 9.5 
per cent after 1 hour and 14 per cent after 19, after 43, and after 91 
hours ; (c) the sulphid sulphur was reduced 8 per cent after 1 hour and 
18 per cent after 91 hours; (d) the thiosulphate sulphur remained 
unchanged after each period; (e) the sulphate sulphur increased 
slightly, although the same increase was observed in the control; and 
(/) 5.2 per cent of the total arsenic oxid of the lead arsenate used was 
rendered soluble. From these results, it is apparent that chemical 
changes have occurred. The mixture is therefore chemically in- 
compatible. 5 Some of the sulphur in lime-sulphur solution probably 
united with the lead of the lead arsenate and produced lead sulphid, 
which could be seen as black particles in the mixture. The arsenic 
oxid group, liberated by the decomposition of the lead arsenate, was 
then free to combine with the lime in the lime-sulphur solution, 
probably forming calcium sulph-arsenate. The formation of in- 
soluble tricalcium arsenate took place only to a limited degree. 
Robinson (34) in examining mixtures of calcium arsenates and 
lime-sulphur found that no reaction took place in such mixtures. 
His tests with "dry lime-sulphur" mixed with calcium arsenate 
showed the presence of no soluble arsenic, but those with " soluble 
sulphur" mixed with calcium arsenate showed that it was present. 
Lovett (24) also reported that no changes take place when calcium 
arsenate is mixed with lime-sulphur solution. 
Experiments similar to the lead arsenate tests were performed, 
using calcium arsenate (sample 57) in place of the acid lead arsenate. 
A series of 500 cubic centimeter flasks were filled with lime-sulphur 
solution diluted 1 to 30. Nine of the flasks were used as controls; 
to each of the others 1 gram of calcium arsenate was added. The 
solutions were agitated for periods of 1 hour, 21 hours, and 5 days. 
They were immediately filtered and the filtrates were tested. 
• The term "compatible" is here used only in the chemical sense. 
