July 15, 1921 
Reduction Strength of Mercuric-Chlorid Solution 
581 
Table III .—Percentage of mercuric chlorid removed from solution by treating 30 pounds 
of washed sweet potatoes in 7 gallons of solution 
Length of treatment. 
Percentage 
of HgCl 2 
present in 
solution. 
Percentage 
of HgCI 2 
removed 
from 
solution. 
Control a . 
99. 6 
97. 2 
97-4 
97. 2 
97. 2 
97. 0 
5 minutes. 
A 
10 minutes. 
2 
30 minutes... 
2. 4 
O A 
60 minutes. 
90 minutes. 
2. () 
* Solution unused. 
A COMPARISON OP THE AMOUNT OP MERCURIC CHLORID REMOVED BY 
IRISH AND SWEET POTATOES 
Since it was customary to recommend that the solution used for 
treating sweet potatoes be discarded after 3 or 4 bushels had been 
treated on the assumption that sweet potatoes would remove from the 
solution about the same amount of mercuric chlorid as Irish potatoes, 
a comparative test with Irish potatoes was made. Six pounds of Irish 
potatoes of the Burbank variety were washed and treated, a sample 
being taken before disinfecting the potatoes and at stated intervals 
thereafter, as shown in Table IV. 
Table IV. — Percentage of mercuric chlorid removed from solution by treating 6 pounds 
of washed Irish potatoes in 2 gallons of solution 
Length of treatment. 
Percentage 
of HgCla 
present in 
solution. 
Percentage 
of HgCla 
removed 
from 
solution. 
Control a . 
07 2 
5 minutes. 
y/* ^ 
06 A 
0. 8 
10 minutes.. 
06 A 
. 8 
30 minutes. 
yw. ^ 
06 A 
. 8 
60 minutes. 
yw. 
06 A 
8 
90 minutes... 
y u * h 
96.0 
T 0 
0 Solution unused. 
The results given in Table IV show that 6 pounds of washed Irish 
potatoes reduced the strength of the mercuric-chlorid solution to a 
slightly less extent than did an equal weight of sweet potatoes (Table 
II). They show further that Irish potatoes, like sweet potatoes, remove 
most of the mercuric chlorid during the first five minutes of treatment. 
