OXIDATION OF ARSENIC IN DIPPING BATHS. 
were analyzed for arsenic in its two forms and were then left at room 
temperature for varying lengths of time, after which they were again 
analyzed. Some tests were carried on in open vessels (beakers) and 
in these the liquid was kept up to its original level or weight by daily 
additions of water to replace loss by evaporation. 
The following detailed experiments are selected as typical from the 
considerable number actually performed. 
Experiment 1. — To determine possible influence of high initial 
percentages of actual arsenious oxid upon oxidation. Total initial 
volumes, 250 c. c, containing 10 c. c. used bath as inoculum. Carried 
out in open 800 c. c. beakers, replacing loss by evaporation. 
Table 1. — Influence of high initial 'percentages of actual arsenious oxid upon oxidation. 
No. of test. 
Per cent actual AS2O3 by analysis. 
Original. 
10 clays. 
20 days. 
30 days. 
0. 200 
.240 
.278 
.316 
.356 
.394 
0. 1S4 
.234 
.276 
.312 
.340 
.362 
0.002 
.068 
.138 
.146 
.176 
.232 
b 
0. 001 
.002 
d 
.002 
.002 
f 
.002 
Experiment 2. — To determine possible influence of high initial 
percentages of total arsenious oxid upon oxidation. Total initial 
volumes, 250 c. c, containing identical initial amounts of actual 
arsenious oxid, but varying amounts of arsenic oxid. Inoculated 
and carried out similarly to experiment 1. 
Table 2. ; — Influence of high initial percentages of total arsenious oxid upon oxidation. 
No. of test. 
Per cent 
total 
As 2 3 . 
Per cent actual AS2O3 by analysis. 
Original. 
10 days. 
20 days. 
30 days. 
a 
0.204 
.244 
.284 
.324 
.364 
.404 
0. 084 
.084 
.084 
.084 
.084 
.084 
0.194 
.226 
.261 
.307 
.314 
.316 
0. 013 
.017 
.129 
.179 
.183 
.189 
£.::: 
0.001 
.002 
d 
.002 
.002 
f 
.001 
Experiment 8. — To determine the rapidity with which reduction 
may progress. Solution contained no actual As 2 3 except that 
introduced in the used bath employed for inoculation, of which 10 
per cent of final volume was added. Solution contained 0.242 per 
cent total arsenious oxid. A portion (test a) was placed in an entirely 
filled, tightly stoppered bottle, and another portion (test b) left 
open to the air as in experiments 1 and 2. 
