IMPROVE- MENTS IN GALVANIC CELLS
Year: 1885

page_text: I, SIEGMUND RAUDNITZ of No 51 Mariahilfer Str. Vienna in the Austrian
Empire, Electrician do hereby declare the nature of said invention for "IMPROVE-
MENTS IN GALVANIC CELLS" and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:-
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These improvements may be divided into two parts. The first part consists in
the employment of a mixture of nitric acid and muriatic acid in statu nascendi as
depolarising fluid.
I employ zinc and carbon electrodes; the zinc may be surrounded by pure water
alone as sufficient acid penetrates the porous cell from outside the carbon electrode,
but it makes no difference of any importanco if the fluid around the zinc pole
consist of dilute sulphuric acid, or of any alkaline liquid, chloride of natrium or
sodium natrium sulfuricum, dilute muriatic acid, etcetera; or dilute chlorides of
mercury may be employed.
As depolarising agent I employ a mixture of three different solutions which is
placed around the carbon electrode, and out of which Aqua regia the aboveinen-
tioned mixture of muriatic acid and nitric acid in diluted solution is formed in
statu nascendi, as soon as the circuit is closed and a current goes through connecting
the two electrodes of zinc and carbon. The three solutions consist of:
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1. From 1 to 2 litres of water with addition of from 2 to 3 kilogramme of
saltpetre (nitrate of soda or kali).
2. From 1, to 2 litres of water with addition of from 1 to 1/2 kilogrammes
of sulphuric acid.
3. From 1 to 2 litres of water with addition of from 12 to 1 kilogramme of
muriatic acid.
Instead of the muriatic acid solution last mentioned, I may employ any solution
of salts containing chlorine, for instance chloride of sodium chloride of kali, or any
mixture of such salts containing chlorine.
This depolarising fluid differs much from the later improvements in galvanic
cells, where nitrate of soda and sulphuric acid are employed and where the action
of the depolarising fluid depends upon the formation of nitric acid alone, and the
current generated, is, like that of the well known Bunsen cell, only of a few hours
duration.

page_text: The action of the depolarising fluid of this invention is as follows: The
hydrogen which appears at the carbon electrode, when the circuit is closed,
decomposes the nitrate of soda, whereby sulphate of soda is formed, this at the
same time being a good conductor offering very little resistance to the current.
Nitric acid is also formed.
One portion of the nascent hydrogen combines with the protoxide of nitrogen
which is formed in the fluid and produces ammonium; and the chlorine of the
muriatic acid or salt solution takes up the remainder of the free hydrogen and
again forms muriatic acid which again combines with the nitric acid and forms the
aforesaid mixture of muriatic acid and nitric acid,-called "Aqua regia "-in statu
nascendi while the circuit is closed.*
This depolarising fluid of "Aqua regia" in statu nascendi and in dilute solutions
produces a powerful and constant current.
The second part of these improvements consists in the arrangement of the carbon
electrodes the top part of which is placed within a brass cap which loosely fits the
carbon, and the space between the brass cap and the carbon plate is then filled up
with molten tin. By this means the carbon is firmly fixed in the metal cap giving
a better conducting carbon as the result. A conducting wire is soldered on to the
outside of the metal cap.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. In galvanic cells the employment of a depolarising fluid termed "Aqua regia"
(mixture of nitric and muriatic acid) in statu nascendi of the composition and in
the manner substantially as described.
2. In galvanic cells the employment of the several solutions specified, mainly
composed of a dilute solution of nitrate of soda or kali, sulphuric acid and muriatic
acid, or any solution of sults containing chlorine for the purpose of producing
Aqua regia" in statu nascendi while the circuit is closed substantially as
specified.
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3. The arrangement of carbon electrodes substantially as described.