July 15, 1921 
Reduction Strength of Mercuric-Chlorid Solution 
579 
strength of mercuric chlorid 5.7 per cent, the second 3.4 per cent, the 
third 2 per cent, the fourth 4.8 per cent, and the fifth 1.8 per cent, or an 
average reduction of 3.54 per cent. The potatoes used in the latter 
experiment had been employed in previous experiments of another 
nature, and some of them had had a considerable part of the dirt removed 
by handling or by being dipped into water. The potatoes used in the 
first experiment, however, had been selected for seed in the autumn, were 
stored in crates, and had not been handled until they were placed in the 
baskets in which they were treated. Nevertheless, data to be presented 
later will make it clear that a considerable amount of variation is to be 
expected. 
I11 both experiments X ounce of mercuric chlorid was added after each 
10 bushels treated, in an endeavor to bring the solution up to its original 
strength. No data were at hand from which the correct amount of 
mercuric chlorid to be added could be calculated. It will be noted that 
in all but one case—namely, in the first experiment—after 20 bushels 
were treated, the amount of mercuric chlorid added was more than 
enough to return the solution to its original concentration. 
Table I shows that within the limits of these experiments the addition 
of X ounce of mercuric chlorid after 10 bushels of potatoes were treated 
sufficed to keep the disinfectant up to a strength where it was probably 
effective for the treatment of a total of 20 bushels without the addition 
of water. However, the thoroughness with which the potatoes are 
drained on removal from the barrel determines to a considerable extent 
the amount of water it is necessary to add. If reasonable care is exer¬ 
cised 20 bushels may be treated without the addition of water. 
MERCURIC CHIyORID REMOVED BY CI^KAN SWEKT POTATOES 
The results obtained by the analyses of the solutions used for disin¬ 
fecting sweet potatoes according to the method already described show 
that a considerable amount of the mercuric chlorid was removed. How¬ 
ever, the results give no clue as to what was responsible for the change 
produced in the concentration of the solution. An attempt was next 
made to determine to what extent the potatoes, the dirt, and the con¬ 
tainer were responsible for the reduction in the strength of the mercuric 
chlorid. 
The ability of potatoes, which were without doubt the most bulky 
substance added to the solution, to take up mercury was tested first. 
Six pounds of sweet potatoes from the storage house were washed free 
from dirt in running water, dried, and then immersed in 2 gallons of a 
solution of mercuric chlorid for 1X hours, a sample being taken before 
the potatoes were added and again at various intervals, as indicated in 
Table II. The solutions of mercuric chlorid used in all of the following 
experiments were prepared separately. 
