Improvements in Producing Nitric Acid and Metals from Nitrates.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in Producing Nitric Acid and Metals from Nitrates.
We, JAMES DOUGLAS DARLING of 5021 Tacony Street, Frankford, Chemist,
and HARRY CLARENCE FORREST, of 6920 Grenloch Street, Tacony, Manufacturer,
both in the City and County of Philadelphia, Pennsylvania, United States of
America, 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 :-
Our invention relates to the production of nitric acid and metallic sodium or
potassium from nitrate of soda or nitrate of potash by electrolizing the nitrate
while it is in a condition of fusion.
The accompanying drawing is a vertical section of a double cell which we
employ in carrying out the process.
A is a vessel made of aluminium or other metal which is not attacked by fused
nitrate of soda or potash, this vessel having a close fitting cover B, bolted or
otherwise securely fixed on the vessel, but insulated from it by an interposed layer a
of insulating material.
The vessel A is divided into two parts by a central partition D of the same
material as the vessel itself, but the two compartments are in communication
with each other through one or more openings through the partition near its
bottom.
In each of the compartments there is a carbon or platinum electrode F carried
by a clamp F which is secured to the cover B and has a transverse and vertical
passage d leading through its upper part.
Surrounding each of the electrodes F there is an inverted cup G also by
preference of aluminium, the top of this cup being clamped between the
cover B and the clamp F, but being insulated from both by suitable insulating
material f
Through the side of each cup G there are numerous openings g inclined
upwardly towards the inside of the cup. Through the cover B passes insulated
from the cover a funnel or hopper I which extends some distance down into the
vessel A.
The operation is conducted as follows.
The vessel A being filled with the nitrate, say for instance, nitrate of soda, is
subjected to heat until the nitrate is fused, the temperature being, by preference,
so limited that the decomposition of the nitrate and liberation of oxygen are
prevented because the hot liberated oxygen would vigorously attack the positive
electrode. When the fusion of the nitrate is completed, the cover B, with its
electrodes, inverted cups and funnel, is fixed on the vessel A and a suitable
generator of electricity is then connected to the cell, the positive pole being
connected to the cover and the negative pole to the vessel A.
The vessel A thus becomes the negative element of the cell and after the
electrical connection is made the degree of heat applied to the vessel A may be
moderated as the electric current tends to maintain the salt in its fused
condition.
The nitrate of soda is electrolized by the action of the current, sodium being
liberated at the negative pole and anhydrous nitric acid and oxygen at the positive
pole.
The anhydrous acid and oxygen issue through the passage d of each clamp F¹
and are then led through Woullf bottles, forming nitric acid whilst the oxygen
esca nes

page_text: The first of the sodium liberated at the negative pole reduces the neighbouring
nitrate of soda forming sodium nitrite and sodium oxide which dissolves in the
sodium nitrite.
Afterwards, both the sodium nitrite and the sodium oxide are decomposed, the
liberated sodium rising to and floating on the top of the fused salts whence it can
be removed at intervals, as for instance, through an aperture s closed by a plug ¹
in the side of the vessel A.
The nitrate of soda may be first heated to a high temperature so as to drive
off as much oxygen as possible and the positive electrodes may then be inserted
and the electrolytic action begun but we prefer to operate as above described.
The object of the perforated cups G is to collect the gases evolved at the
positive pole and direct them to the hollow clamp F', thus preventing them from
spreading through the fused salts and coming into contact and combining with the
liberated metal.
As the level of the fused salt in the vessel A is lowered by reason of the
decomposition of the salt, fresh salt is fed through the funnel I which
extends into the fused salt and is thereby sealed in order to prevent the
access of air.
Although we have shown in the drawing a double cell, it will be evident that
our invention may be carried out in a single cell, or in a cell having any desired
number of electrodes.
In some instances the cups may be made of different lengths and when a partial
vacuum is maintained in the Woullf bottles the cups may be dispensed with.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
The herein described process for obtaining nitric acid and metallic sodium or
potassium from nitrate of soda or potash by electrolyzing the salt while it is in a
state of fusion in a closed vessel collecting the metal at the negative pole, leading
off from the positive pole the nitrogen peroxide there formed and converting the
nitrogen peroxide into nitric acid.
Dated this 20th day of March 1894.
ABEL & IMRAY,
Agents for the Applicants.