188 Proceedings of Indiana Academy of Science 
cup type of silver coulometer as the standard for the measurement of 
electrical current. As already mentioned, the manipulation of the cou- 
lometer in the present work would not give the high degree of ac- 
curacy attained by Richards and Anderegg, but it seems probable that 
the error involved in these measurements is small. 
The second source of error to be considered is in the analytical 
methods used for the determination of the lead. In the handling of the 
peroxide the chief difficulty has been in drying the deposit under con- 
ditions that will remove all the water and yet not convert any of the 
peroxide to monoxide. This determination has been worked over many 
times and Smith finally recommends drying at a temperature of at 
least 200° C., when the error involved is stated to be small. The dry- 
ing in this work was made from 230° to 300° C. No appearance of the 
yellow monoxide was noted; if there had been some undetected, the 
results calculated would be lower than otherwise, owing to the fact that 
the deposit would weigh less than if there were no such conversion. 
In one set the values for the peroxide were checked by conversion to 
the monoxide and weighing as such. Although it may be possible that 
the combined errors of the coulometer and the general manipulation 
could account for the difference between the lead at the anode and the 
lead equivalent of the silver, it does not seem probable. 
If one uses the empirical factor 0.853 of Hollard* for lead in lead 
peroxide instead of the theoretical value of 0.866 in calculating the re- 
sults for Table II, a considerable difference is noted in the relation- 
ships involved. These values have been inserted in the table in the 
parentheses. It will be noted that the ratio of the lead deposited at 
the anode to the lead equivalent of the silver falls in all the cases con- 
sidered to values much closer those for the ratio of the lead deposited 
at the cathode to the lead equivalent of the silver. In some cases they 
are very close together. The average of these anodic ratios becomes 
0.990 as compared with 0.986 for the cathodic ratios. These values 
indicate the deposition of an amount of lead at each electrode slightly 
less than the electrochemical equivalent of the silver deposit. 
For the determination of the lead in the amalgam the data pre- 
sented by the authors in the preceding paper indicates that the method 
employed is accurate. These results showed that the weight of lead not 
recovered by this procedure was less than 0.1 per cent of that originally 
added to the mercury. The error in this determination would not seem 
to account for the variation of 1.4 per cent between the lead found and 
the lead equivalent of the silver. 
ParT IIJ—SuUMMARY. 
In this work involving the electro-deposition of lead from aqueous 
solutions of the nitrate, there has been presented: 
1. A review of the investigations bearing upon the division of 
lead between the two electrodes during the electrolysis. 
2. Data associated with the quantitative relationship betwen the 
anodic and cathodic deposits of lead, and the relationship between these 
and the deposit of silver in a coulometer. 
Department of Chemistry, Purdue University. 
1]bbotson and Aitchison—Analysis of Non-Ferrous Alloys, p. 60 (1915). 
