58° 
Journal of Agricultural Research 
Vol. XXI, No. 8 
Table II .—Percentage of mercuric chlorid removed from solution by treating 6 pounds 
of washed sweet potatoes in 2 gallons of solution 
Percentage of HgCl> 
present in solution. 
Percentage of HgCh 
removed from solu¬ 
tion. 
Length of treatment. 
- - -- 
- - . 
Experi- 
Experi- 
Experi- 
Experi- 
ment 1. 
ment 2. 
ment 1. 
ment 2. 
Control & . 
98. 2 
97. 2 
IOO. O 
5 minutes. 
98.8 
I. O 
I. 2 
10 minutes. 
96.9 
9®- 3 
1-3 
7 
30 minutes. 
60 minutes. 
96.8 
97. 1 
97. 2 
98. O 
-• 4 
T. T 
2. O 
90 minutes. 
98. O 
I. O 
2. O 
« Solution unused. 
The control in Table II and in other tables to follow shows the concen¬ 
tration of the solution before the potatoes were added. In experiment i 
there was a decrease of i per cent in the amount of mercuric chlorid 
present after 5 minutes and a decrease of 1.3 per cent, 1.4 per cent, 1.1 
per cent, and 1 per cent after 10, 30, 60, and 90 minutes, respectively. 
These results may seem inconsistent, but as a matter of fact the varia¬ 
tions are well within the limits of experimental error, since a difference 
of 0.3 per cent is equivalent to only 0.05 cc. of potassium iodate. It is 
evident, then, that the potatoes removed approximately 1 per cent of 
the mercuric chlorid during the first 5 minutes and no appreciable amount 
thereafter, at least up to \]/ 2 hours. 
Experiment 2 was an exact duplicate of experiment 1, except that no 
sample was taken at the end of 60 minutes. Here there was a reduction 
in mercuric chlorid of 1.2 per cent after 5 minutes, 1.7 per cent after 10 
minutes, and 2 per cent thereafter up to the end of the experiment. 
Again the greatest decrease occurred during the first 5 minutes, followed, 
however, by a further slight reduction during the next 5 minutes. The 
reduction of 0.3 per cent after 30 minutes is well within the limits of 
experimental error. 
These two experiments show that the greatest reduction in the con¬ 
centration of the mercuric chlorid took place during the first 5 minutes 
of treatment. However, it was thought desirable to conduct a similar 
experiment on a larger scale. Accordingly 30 pounds of washed potatoes 
were treated in 7 gallons of mercuric-chlorid solution, and samples were 
taken for analysis, the results of which are given in Table III. 
The results show a reduction of 2.4 per cent in the amount of mercuric 
chlorid at the end of the first five minutes, the concentration remaining 
practically constant thereafter. These experiments show that the 
sweet potatoes removed some of the mercuric chlorid from the solution 
and that by far the largest part was taken out during the first five min¬ 
utes. 
