Lead and Lead Peroxide 185 
side the platinum dish serving as cathode for the coulometer, and about 
0.5 cm. above the bottom, the porcelain cup was suspended. The silver 
wire in the form of a spiral was lowered close to the bottom of the 
cup. After filling the dish nearly full, and the cup slightly below this 
level, with a 5 per cent solution of silver nitrate, the current was allowed 
to pass from 1 to 3 hours. At the end of this time, the solutions in 
the three cells were siphoned off simultaneously, being replaced with 
distilled water until the ammeter in the electrical circuit indicated prac- 
tically no current passing. The weights of silver and lead deposited 
were then determined according to the methods already outlined. 
The solution of lead nitrate used as electrolyte for the determina- 
tions reported in Table II was made by dissolving an amount of the 
salt in water to produce an approximately 10 per cent solution. For 
the second series, the solution was made by diluting 40 cc. of concen- 
trated nitric acid to 1 liter with the previous solution; and the third 
solution was made in the same way, using 80 cc. of the nitric acid. 
The value for the lead equivalent of the silver deposited was ob- 
tained by multiplying the weight of the silver for each determination 
by the ratio obtained in dividing one-half of the atomic weight of lead 
(207.20) by the atomic weight of silver (107.88), this ratio being 0.9603. 
The factor used for lead in lead peroxide was 0.866. 
The quantities reported for lead as lead peroxide and for lead as 
lead amalgam are the average of the two cells run in each experiment. 
The values reported as variations from the average indicate the amount 
by which each determination varied from the average of the two. The 
amperage showed some variation during the electrolysis, and the values 
recorded are taken as the average. Table I includes some preliminary 
results, and Table II those obtained in the later work. 
TABLE I. 
Deposition of Lead from Aqueous Solutions of Lead Nitrate. 
No. Time in Hours Milliamperes Lead as Peroxide | Leadas Amalgam | Ratio of Anode Lead 
to Cathode Lead 
1 3.0 20 0.2383 0.2329 1.0232 
2 3.0 20 0.2489 0.2294 1.0850 
3 3.0 20 0.2505 0.2384 1.0508 
4 3.0 24 0.3098 0.2979 1.0399 
5 5.5 10 0.1993 0.1870 1.0657 
6 4.0 14 0.2099 0.1932 1.0864 
7 4.0 19 0.3229 0.3040 1.0621 
The investigation reported in this paper was begun at The Ohio 
State University in 1919 by C. C. Curran under the direction of the 
senior author. The results in Table I, obtained at that time, when 
compared with those in Table II, show the effect of employing more 
refined methods of analysis. 
In this earlier work a copper coulometer was used, but the results 
obtained with it indicated inaccurate manipulation. The lead peroxide 
was weighed after drying at 105° C.; and the metallic lead was ob- 
tained from the increase in weight of the mercury cathode, after being 
washed with water, alcohol and ether. These determinations include 
