Year: 1889

page_text: CARL HERMANN MEHNER of 37 Kastanienallee Berlin 28 in the Kingdom of
Prussia and German Empire Doctor of Philosophy do hereby declare the nature
of this Invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:—
In dry galvanic cells or elements for electric batteries as heretofore constructed
it is usual to employ as the vehicle for the exciting liquid a neutral or inactive
material which absorbs the liquid excitant and forms therewith a stiff pulp or paste
or imparts to it a gelatinous consistency. The materials commonly employed for
this purpose are sponge, sawdust, gypsum, gelatine and the like. It is evident that
the introduction of these inactive materials is prejudicial to the action of the cell the
said materials forming an encumbrance which apart from its purely mechanical
action in no way promotes but on the contrary tends to diminish the effective working
of the battery.
In order to dispense with this dead or inactive matter I impart the required
firmness or consistency to the exciting agent by treating or preparing it as hereinafter
described. With this object I mix the exciting salts consisting of suitable chlorides
of the alkalies or earthy alkalies for example with a mineral gelatine. This gelatine
holds or retains the salts in a paste or pulp-like mass and possessing exciting properties
in itself also acts as an exciting agent.
The aforesaid mineral gelatine" consists of crystallised hydrated basic chloride
of magnesium which 1 form by the addition of magnesia into a highly supersaturated
and concentrated solution of magnesium chloride. If a suitable quantity of the
solution of magnesium chloride is added to the oxide of magnesia for example
in the first instance a solid substance is not formed as in the manufacture
of Sortel cement but a liquid product results being of a creamy consistency at first
gradually gelatinising and ultimately acquiring a pasty consistency. The degree of
stiffness or consistency of the final product can be readily controlled by suitably
regulating the addition of chloride solution. I avail myself of this property of
oxy-chloride of magnesium in the preparation of the dry galvanic cells according
to my present invention. With this object I stir the exciting salt with a solution of
chloride of magnesium and calcined magnesia until 1 obtain a liquid of about the

page_text: thickness of cream which I pour into a cell or element constructed with suitable
electrodes such as zinc and brown coal or other carbon. In the course of a few days
the liquid changes to a stiff pulp or magma and the cell or element can then be
closed. Or the mass may be heated with the addition of water.
The materials remain liquid until cold the salts being highly soluble in the heated
liquid. On cooling the mass sets or stiffens and forms a stiff pulp or magma. The
mineral gelatine being in itself a substance capable of producing an exciting action
in a galvanic. cell or couple the employment of an inactive or "dead" material is
entirely obviated and the efficiency of the cell proportionately increased.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is―
In a dry galvanic cell the employment of basic chloride of magnesium formed with
an excess of neutral salt with water of crystallisation for the purpose of converting
the exciting liquid into a nonflowing pasty or gelatinous mass substantially as herein-
before described.