720 
CHEMISTRY: BAXTER AND STARKWEATHER 
ings, and the whole further electrolyzed. At the completion of the 
electrolysis the electrolyte was displaced successively with water and 
pure alcohol, both of which had been freshly saturated with hydrogen. 
To dry the amalgam the cell was placed in a small desiccator and the 
pressure reduced as far as possible. The electrolyte was evaporated, 
at first in a quartz dish, later in a weighed platinum crucible, and the 
residue heated gently. The weight of tin, computed upon the assump- 
tion that the residue was stannic sulphate, was added to that found 
in the amalgam. Although complete precipitation of the tin was never 
secured, the residue usually did not exceed 2 mg. in weight, and was 
never as much as 4 mg. Repetition of the electrolysis, after dissolv- 
ing the residue in dilute sulphuric acid and returning it to the cell, 
sometimes caused a slight decrease in the weight of tin recovered. In 
all cases constant weight within 0.1 mg. was finally secured. 
As a check upon the accuracy of this method of determining tin, in 
two experiments a weighed ingot of pure tin was electrolytically trans- 
ported from the anode to the mercury cathode of the weighed cell. 
In one case a gain of 0.01 mg., in the other a loss of 0.06 mg. was 
observed. Such small changes are less than the probable error of weigh- 
ing the cells. 
The experimental data and the results calculated from them (assum- 
ing the atomic weight of chlorine to be 35.457) are shown in the follow- 
ing table. The weights of the bulbs containing the stannic chloride, 
of the glass and of the tin dissolved in the mercury are all corrected to 
vacuum. 
Series 
Fraction 
Grams of 
SnCU 
Grams of 
Sn 
Ratio 
Sn:Cl4 
Atomic weight 
of Sn 
I 
5 
11.64269 
5.30498 
0.837050 
118.717 
I 
7 
13.5943 
6.1935 
0.83687 
118.691 
I 
8 
10.0897 
4.5971 
0.83696 
118.705 
I 
9 
11.4319 
5.2080 
0.83677 
118.678 
I 
11 
12.2869 
5.5983 
0.83699 
118.709 
I 
12 
12.20889 
5.56286 
0.837020 
118.713 
I 
13 
10.7469 
4.8965 
0.83695 
118.703 
I 
14 
11.54233 
5.25846 
0.836818 
0.836929 
118.684 
118.700 
II 
2 
15.65437 
7.13198 
0.836852 
118.689 
II 
3 
16.23310 
7.39664 
0.837059 
118.718 
II 
4 
17.29151 
7.87850 
0.836980 
118.707 
II 
7 
15.04889 
6.85695 
0.837037 
118.715 
II 
8 
18.36074 
8.36507 
0.836869 
118.692 
II 
9 
21.58929 
9.83676 
0.836991 
118.709 
II 
10 
17.22210 
7.84718 
0.837040 
118.716 
II 
11 
15.70516 
7.15589 
Average 
0.837018 
0.836981 
0.836955 
118.713 
118.707 
118.703 
