OXIDATION OF ARSENIC IN DIPPING BATHS, 
9 
have two fully developed opposing forces in the vat — one tending to 
oxidize the arsenic, the other to reduce it. Which agency will gain 
the ascendency at any given time will depend chiefly on the quantity 
and frequency with which cattle are being put through, the bath, 
Frequent and abundant use of a bath will favor reduction; limited 
and infrequent use will favor oxidation. The oxidizing organisms 
must be conceived as working slowly but steadily and persistently 
under all conditions of use: the reducing organisms may work very 
rapidly when they work at all, but they work only spasmodically 
during ordinarily brief periods when the bath happens to be suffi- 
ciently rich in nutrient matter. 
The next series of experiments were upon the effectiveness of cer- 
tain antiseptics against the activity of both reducing and oxidizing 
organisms, with the double purpose of finding (1) a reliable means 
for preserving samples for analysis after removal from the vat and 
(2) a practical means of preserving the bath in the vat. 
Experiment 4- — To determine if a layer of oil floated over the sur- 
face of the bath during periods of disuse would prevent oxidation. 
Mixture made in the usual way, placed in beakers, and covered with 
layers of oil of approximate thicknesses noted below. 
Table 4. — Effect on oxidation of oil floated over surface of bath. 
No. of test. 
a (no oil) 
b (1 mm. paraffin oil).. 
c (0.1 mm. paraffin oil) 
d (no oil) 
e (1 mm. kerosene) 
Per cent actual AS2O3 by- 
analysis. 
Original. 6 days. 10 day 
0.255 
.255 
.255 
.194 
.194 
0.185 
.219 
.204 
0.003 
.219 
.009 
.013 
.033 
Experiment 5. — On the efficacy of cresylic acid as an antiseptic 
against oxidation. Mixtures made in the usual way, certain pro- 
portions of cresol being added in the form of liquor cresolis compositus^ 
U. S. P. 
Table 5. — Effect of cresylic acid as an antiseptic against oxidation. 
No. of test. 
Per cent actual As 2 3 by 
analysis. 
Original. 
days. 
10 days. 
a (no cresol) 
b (0.004 per cent cresol) 
c (0.02 per cent cresol) . 
d (0.10 per cent cresol). 
e (0.50 per cent cresol) . 
0.201 
.201 
.201 
.201 
.201 
0.027 
.106 
.146 
.183 
.185 
0.006 
.003 
181 
