W. C. May—Determination of Lead as Peroxide. 255 
Art. XX VII.—Chemical Papers from the Massachusetts Institute 
er- 
of Technology.—No. II. The determination of Lead as Pi 
oat y W.C. May. 
In the account of Luckow’s scheme of analysis of copper 
given by the 
main portion has been precipitated by sulphuric acid. In 
order to discover whether this method is serviceable for the 
estimation of larger quantities of lead, the following experi- 
ments were made. 
The substance operated upon was brass, the per cent of 
copper and lead in which were accurately known from a 
and diluted with water, so that for one gram of copper about 
80 to 100 c.c. of water and 3c.¢. of strong nitric acid were 
eet in addition to the acid combined with the metals. 
€ metals were precipitated by the galvanic current, the 
: sitive elec- 
Washed and was then weighed in the usual manner. — The oxide 
“ss lead precipitate, I satisfied myself, was virtually insoluble in 
hitric acid of the strength here used, and therefore deemed it 
unnecessary to continue the current after the copper had been 
temoved from the solution. All chance of error in this respect 
might be avoided by connecting a platinum wire with the bat- 
tery, in place of the negative electrode, and immersing it in 
the solution. A fter drying and weighing the copper, the lead 
* Fresenius Zeitschrift, 1869, p. 1. 
