IMPROVEMENTS IN VOLTAIC BATTERIES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Leo Hartmann at the Office of the
Commissioners of Patents on the 22nd November 1882.
_LEO HARTMANN of N° 55 Middleton Square in the County of Middlesex
"IMPROVEMENTS IN VOLTAIC BATTERIES"
My Invention relates to the construction of voltaic batteries and the preparation
and application of their elements in such a manner as to render the electrical
production very uniform over long periods of time. For this purpose I employ zinc
as the positive element and silver as the negative element, arranging the silver in a
manner which I will presently describe, and I employ as exciting liquid solution of
caustic potash or soda. The zinc occupies the middle of each cell and may be
surrounded by a porous partition, the silver being at the sides, not in one plate or
mass but in a subdivided form so as to present in comparatively small space a
large amount of surface with numerous interstices for escape of the hydrogen.
Thus in front of the walls of the cell I fix a network which may be of metal or of
vegetable fibre coated with frosted silver, and between this network and the cell
wall I place a number of fragments of carbon which as well as the cell wall are
also coated with frosted silver. The cell wall and network if metallic or of material
partially conductive of electricity and the carbon fragments can be coated with the
silver electrolytically. The vegetable fibre is coated in the following manner.
It
is first immersed in a solution of gallic acid then in a solution of nitrate of silver.
After being dried it is again immersed in a solution containing grape sugar, tartaric
acid and lime, and finally in a solution of ammoniauret of silver. I prefer to fix
in the lower part of the cell a funnel baving a small mouth opening down to a
space below the cell where the oxide of zinc collects, the funnel forming nearly a
complete separation between this oxide and the elements above, and so reducing
greatly the tendency to cross action by polarisation. I prefer also to cover the cell
with glass to prevent as far as possible access of carbonic acid to the exciting
alkali, leaving however a small passage for issue of the hydrogen generated. A
number of cells may be grouped together in one box, these cells being insulated
from one another if they are made of metal. The cells may however be made of
wood by dividing by partitions a wooden box, all the wood employed being water-
proofed by soaking it in paraffin or other waterproofing material. I connect each

page_text: cell by a tube of glass or other non-conducting material to an external supply
reservoir turning the ends of the tubes all up to one level in the reservoir which is
when required supplied with distilled water. The lower parts of the cells below the
funnels may all in like manner be connected with a discharge reservoir from which
the liquid containing oxide of zinc may from time to time be discharged. Each cell 5
may however be discharged separately by opening a passage at its bottom. When
tubes are employed as above described for communicating with the separate cells
either for supply or for discharge or for both, these tubes may conveniently be
accommodated in grooves in the partitions of the-box.---