3 
Battery B. Liquid from outside cup. Same result pre- 
cisely. 
Local action does not produce ammonia in important 
quantity. 
January 26th, 18738. Set upa single cell, Grove form, 
with dilute sulphuric acid in the outside cup, and a mixture 
of equal parts of saturated solution of potassic nitrate and 
Kalbfleisch’s commercial oil of vitriol in the inside cup. 
Proved in advance that each liquid was free from ammonia. 
After 24 hours, tested both liquids for ammonia, That 
from the inner cup contained great quantities ; but that from 
the outer one gave no indication of it. 
February 1st, 1873. Set up a single Grove cell, with nitric 
and dilute sulphuric acids. Immediately after setting up, and 
before closing circuit, tested both liquids for ammonia. The 
nitric acid gave no trace; the sulphuric acid gave a faint 
ammonia reaction, and yielded a trace of nitric acid, which 
probably got into it by diffusion through the porous cup. 
Ten minutes after putting the battery in operation, ammonia 
in Jarge quantity was found in the inner cell. 
The conversion of nitric acid into ammonia must be taken 
into consideration in preparing the nitro-chromic battery 
fluid, as proposed by me in the Journal of the Franklin 
Institute, vol. LIx, page 876; inasmuch as enough nitric acid 
must be used to provide an excess over and above the 
quantity converted into ammonia during the time which 
elapses before the last molecule of chromic acid is reduced to 
chromic oxide. 
Mr. Levison’s paper was discussed by Professors Leeds 
and Seely. 
Mr. JAMES GALLATIN, JR., exhibited and explained an 
improved adjustment, by which the carbon points of a 
battery can be kept steadily in the focus of the lens. The 
instrument is automatic, giving notice if at any time the 
points are not in the proper position. . . 
Dr. A. H. GALLATIN mentioned that a constant and steady 
light had been maintained for two hours, by means of this 
instrument. 
A more detailed account of the adjustment is reserved 
until some contemplated improvements shall have been 
finished. 
