36 On Electrical Influence. 
treatment of glass with potash, a part of the yellow oxide 
of lead which enters into its composition, had been decom- 
posed into metallic lead and brown oxide ; that this decom- 
position was produced in virtue of the affinity of lead for. 
platina, and of that of the yellow oxide of lead for an excess 
of oxygen. 
I am of opinion, that in this case the patash does 
not determine the hyperoxidation of the lead, by the 
affinity which it can exercise over the oxide at the maxi- 
mum, as happens with the oxide of tin at the minimum 
dissolved in potash. I found my opinion upon the circum 
stance of the potash having more affinity for the yellow 
oxide of lead than for the brown oxide; for, in the operation 
which I have described, the latter oxide had not been dis- 
solved in the water. with the alkali; whereas the portion of 
yellow oxide which had not been altered was dissolved al- 
most entirely. To conclude: the crystalline form of the 
brown oxide of lead proves clearly, that it bad been at first 
in solution, and that it was afterwards separated from its 
solvent, probably upon cooling. 
It results from what I have detailed, that the platina 
which is in contact with yellow oxide of lead performs 4 
part analogous to that of the nitric acid which acts upon the 
minimum ; with this difference, howeyer, that the platina, 
not being capable of being combined with the oxide of 
Jead, determines the complete reduction of the oxide which 
it attracts; whereas the nitric acid only determined, in the 
minimum, the scparation of that part of the oxygen which 
refuses to combine with the yellow oxide: in both cases, 
the affinity of the yellow oxide and of the red oxide for an 
excess of oxygen concurs in the result. . 
VI. On Electrical Influence. ByGrorcE Joun SINGER, Esqe 
Lecturer on Experimental Philosophy and Chemistry. 
To Mr. Tilloch. 
Sin,— Lue phenomena observed by your correspondent 
E. Walker, Esq. with Mr. Bennet’s gold-leaf electrometer 
have been long familiar to electricians, and are illustrated 
in most elementary works by experiments with electrome- 
ters attached to mmsulated metallic rods: With such an 
apparatus anomalies are Jess likely to accur than by the 
employment of the limited surface of an electrometer-cap, 
and the fecbly excited body necessarily employed with it. 
. Such 
