BULLETIN 259, U. S. DEPARTMENT OF AGRICULTURE. 
Table 3. — Showing rapidity of reduction . 
No. of test. 
Per cent actual AS2O3 by analysis. 
Original. 
2 days. 
11 days. 
20 days. 
a (sealed) 
0.021 
.021 
0.183 
.183 
b (open) 
0.142 
0.002 
From a consideration of the results of experiments 1,2, and 3, we 
may derive the following conclusions: 
1. No amount of arsenic which can reasonably be used in a dipping 
bath is sufficient notably to retard the rate of oxidation or of reduc- 
tion, though naturally a longer time is required for the complete 
oxidation of a large amount of arsenic than for a small amount. 
2. Under conditions favorable to reduction the action may progress 
with extraordinary rapidity, far overbalancing any simultaneous 
opposing action of oxidizing organisms. But in such cases the reduc- 
ing organisms comparatively soon exhaust either their vitality or 
the medium and thereafter are unable successfully to oppose the 
slow but persistent action of the oxidizing organisms. 
One must proceed very cautiously in transferring any conclusions 
drawn from such laboratory experiments to the far different condi- 
tions which prevail in actual dipping baths in the field. None the 
less, taking all available data from field and laboratory into con- 
sideration, it is believed that a fairly accurate picture may now be 
drawn of the conditions which prevail in dipping baths in actual use. 
Suppose a vat to have been thoroughly cleaned and then charged 
with freshly prepared bath. All the arsenic will exist in the form of 
sodium arsenite and, if the bath be not used for dipping, will remain 
in that form except for a comparatively unimportant oxidation 
through purely chemical agencies. But as soon as the bath is used 
for dipping three additions are made to it: (1) oxidizing organisms; 
(2) reducing organisms; (3) nutrient matter upon which one or both 
of the varieties of microorganisms can subsist. At first, of course, 
the number of organisms are few and the nutriment is scanty. Under 
these conditions the reducing organisms do not thrive, but the oxi- 
dizing organisms are able to grow to a certain extent, and thus are 
able slowly to oxidize the bath. As further dipping is done in the 
vat, the bath becomes richer in nutrient matter, so that the oxidizing 
organisms flourish correspondingly and oxidize the arsenic with 
increasing rapidity. But after a time, if dipping is done in sufficient 
amount and at short intervals, the bath becomes so rich in nutrient 
matter that it finally forms a favorable medium for the growth of 
the reducing organisms, which then begin to flourish and appreciably 
to counteract the action of the oxidizing organisms. We thereafter 
