Galvanic Cells.
Year: 1889

page_text: COMPLETE
SPECIFICATION
Dry Galvanic Cells.
I, CARL HERMANN MEHNER, of 37 Kastanienallée Berlin 28 in the Kingdom of
Prussia and German Empire. Doctor of Philosophy, do hereby declare the nature of
my said invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement
In most of the dry cells, now in use, some substance of a neutral or indifferent nature
such as sponge, sawdust, plaster of Paris, gelatine etc. is generally employed to absorb
the exciting fluid in such a manner as to form a pasty or viscous mass.
The employment of such neutral substances is evidently disadvantageous to the
action of the cell, as the former is only an inactive ballast, which takes no part beyond
its purely mechanical function-in the electric action of the element.
In order to avoid the employment of such inactive substances, I have given the
exciting mature the necessary pasty consistence by means of suitable compositions
and attain this result by combining the exciting chemical solutions,-which consist
of chlorids alkalies and basic earths with a "mineral gelatine," which form with
the above solutions a pasty or Jelly-like substance and as the mineral gelatine is in
itself an excitant, the whole mixture acts collectively as an exciting compound.
To make this mineral I employ deliquoscent oxychloride of magnesia, which I
produce by adding magnesia to a concentrated solution of chloride of magnesia
When I add the necessary quantity of chloride of magnesia solution to the oxide, a
creamy liquid is formed, which gradually acquires a pasty consistence, but does not
harden like Sorel's cement. I am enabled to iegulate the desired ultimate consistence
of this mixture by merely graduating the quantity of the chloride solution, which is
added.
Having observed this property of oxychloride of magnesia, I utilize it to produce
my dry-elements. For this purpose I stir together the exciting substance chloride
of magnesia and calcined magnesia till they attain a creamy consistence in accordance
with the process as above described. I now pour this mixture (instead of adding
solution of salammonia as required in the fluid cells) into the cell, which lattei
consists of a cylinder of zinc and an internal concentric cylinder of depolarising
carbon this carbon is composed of a mixture of ordinary carbon with peroxide of
manganese
The above substance, which is at first liquid gradually solidifies to a pasty mass in
the course of a few days, after which the cells can be sealed. Or 1 heat the whole
mixture, while adding sufficient water In this case it remains liquid as long as it
Is warm, because the salts are more soluble in the heated fluid. When cold the
mixture solidifies to a stiff, viscous mass
As my mineral gelatine is in itself an excitant I have by the above method avoided
the employment of any kind of neutral or inactive ballast and thus attained a marked
improvement in the resistance, life and action of galvanic cells I have also found,
that the addition of sulphate of zinc to the above mixture increases its conductivity
its homogenity and renders the cell more constant.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what
I claim is
I claim in the manufacture of dry-cells the employment of deliquescent oxy-chloride
of magnesia with or without the addition of sulphate of zine, which mixture is in

page_text: itself an excitant, for the purpose of transforming the exciting fluid used, into a stiff
pasty or viscous mass, which has no flowing properties; substantially as described.
Dated the fith day of May 1880
CARL HERMANN MEHNER.
By Cheesbrough & Royston,
Agents.