July 15, 1921 
Reduction Strength of Mercuric-Chlorid Solution 585 
These figures show that practically no mercuric chlorid was removed 
from the solution during the first 10 minutes. However, in 2 hours the 
strength was reduced 3.5 per cent, and in 24 hours 9.8 per cent. These 
results demonstrate that although concrete does not remove the mercuric 
chlorid as rapidly as some of the other materials used, yet it does cause 
reduction in strength. 
barrel 
Table IX gives the results of analyses of samples taken from a solution 
made up in a clean oak barrel. These results show that no appreciable 
loss of mercury could be detected up to the second hour, when 1.5 per 
cent had been removed. After 24 hours the strength of the solution was 
reduced 9.7 per cent. Obviously the barrel also exerts an influence upon 
the strength of the solution. 
Table IX .—Percentage of mercuric chlorid removed from solution by a clean oak barrel 
Length of treatment. 
Percentage 
of HgCl 2 
present in 
solution. 
Percentage 
of HgClj 
removed 
from solu¬ 
tion. 
Control 0. 
100. 1 
10 minutes. 
100.5 
100.1 
O 
30 minutes. 
O 
60 minutes... 
100.1 
O 
2 hours. 
98.6 
90.4 
1 . 5 
24 hours. 
sj 
Q. 7 
7 1 
o Solution unused. 
GENERAL DISCUSSION 
From a survey of the tables it is evident that several factors may be 
responsible for the removal of mercuric chlorid from solutions used for 
treating sweet potatoes. No doubt the potatoes themselves remove a 
major portion of it, but other materials which come in contact with the 
solution, such as the sacks, hamper, soil, barrel, or concrete, also reduce 
the concentration of the solution. In the two experiments of which the 
results are recorded in Table I, the method of treating the sweet potatoes 
in common use among growers was used. Here potatoes, dirt, hamper, 
and barrel were all present, and the average amount of mercuric chlorid 
removed by them was approximately 1 per cent for each bushel treated. 
There was considerable variation in the amount removed by each 5 
bushels treated, probably due at least in part to the amount of dirt cling¬ 
ing to the potatoes and to the differences in their size. By the addition 
of K ounce of mercuric chlorid after each 10 bushels of potatoes treated 
the solution was kept near enough to its original strength for all prac¬ 
tical purposes. However, ounce of mercuric chlorid in most cases 
was a little more than enough to restore the solution to its original 
48496°—21 -6 
