Improved Process for the Production of Nitrites of the Alkali or Alkaline Earth Metals.
Year: 1897

page_text: Date of Application, 29th Mar., 1897
Complete Specification Left, 27th Sept., 1897-Accepted, 19th Mar., 1898
Date of Application, on Mar., 1897
Complete Specification Left, 27th Sept., 1897-Accepted, 19th Mar., 1898
PROVISIONAL SPECIFICATION.
Improved Process for the Production of Nitrites of the Alkali or
Alkaline Earth Metals.
We, JOHN MCGOUGAN, Analytical Chemist, and ANGUS MCGOUGAN, Clerk, both
of 14, Maxwell Road, in the City of Glasgow, do hereby declare the nature of
this invention to be as follows:
The object of this invention is the production of the nitrites of the alkali or
alkaline earth metals by the action of lead sulphide (galena) on the corresponding
nitrates of these alkali or alkaline earth metals, preferably in the presence of
caustic alkali; plumbates, oxides of lead and sulphates of the alkali or alkaline
earth metals being recoverable as bye products.
To that end we by preference take the nitrate of soda and caustic soda in
suitable quantities and melt these in a vessel, the requisite amount of finely
powdered lead sulphide (galena) being added in small quantities at a time.
Nitrite of soda, sulphate of soda and litharge are produced and the reaction at
this point may be arrested. The nitrite of soda and sulphate of soda are separated
from the insoluble litharge by their solution in water, they themselves being in
turn readily separated by crystallization.
The action is presumably the oxidation of lead sulphide by the nitrate of soda
into lead sulphate, which in the presence of caustic alkali forms litharge and
sulphate of the alkali.
Instead of arresting the reaction as soon as nitrite of soda, sulphate of soda
and litharge are produced, we may by further addition of definite quantities of
nitrate of soda and caustic soda, and allowing the reaction to continue, prepare
nitrite of soda, sulphate of soda and sodium plumbate, and arrest the reaction at
this point; or the same products can be obtained directly by using the necessary
quantities of nitrate of soda, 'caustic soda and lead sulphide (galena) at the
beginning of the process.
These products may also be readily separated. The nitrite of soda and sulphate
of soda being dissolved out from the almost insoluble sodium plumbate. The
nitrite is in turn separated from the sulphate of soda by crystallization.
In this secondary action the litharge presumably unites with the caustic alkali
in the presence of sodium nitrate, forming alkaline plumbate, and from alkaline
plumbate the peroxide of lead and from the peroxide, red lead can be prepared by
any of the ordinary methods.
If however instead of arresting the reaction when nitrite of soda, sulphate of
soda and sodium plumbate are produced, we continue the reaction, we can by an
increase of temperature prepare nitrite of soda, sulphate of soda and red lead. These
products can also be prepared directly by the same process by heating definite
quantities of sodium nitrate, caustic soda, and lead sulphide (galena) at a slightly
higher temperature.

page_text: Separation can be made by dissolving the sodium nitrite and sodium sulphate
from the insoluble red lead, the former substances being in turn separated by
crystallization.
JOHN MCGOUGAN.
ANGUS MCGOUGAN.
The separation is conducted as previously explained.
If however we take quantities of lead sulphide, nitrate of soda and caustic soda,
as demanded by the following equation, we can produce nitrite of soda, sulphate
of soda and plumbate of soda, thus

page_text: latter is required in the reaction than is shown in the equation before
mentioned. When this reaction is complete the mass is treated with
water and the plumbate of soda present as a yellow precipitate can
either be changed into peroxide of lead in the solution by any of the
common methods (as for example boiling with water or treatment with acid)
or it can be separated from the solution by filtration. On the solution being freed
by filtration or by decantation from the plumbate of soda, or peroxide of lead as
the case may be, the product sodium nitrite and the remaining byeproduct sodium
sulphate and the caustic soda present can be separated by fractional crystallization.
The action presumably is the oxidation of the lead sulphide (galena) by the
nitrate of soda into sulphate of lead, which in the presence of caustic soda forms
litharge. The litharge thus formed simultaneously dissolves in the caustic soda
present to form sodium plumbite; the latter being immediately oxidised by the
nitrate of soda into sodium plumbate. Réd lead can be obtained from the
peroxide of lead by any ordinary method.
Red lead can also be obtained as a byeproduct in the melt reaction, by taking
such quantities of sod ium nitrate, caustic soda and lead sulphide (galena) as will
represent the quantities necessary for the production of lead oxide (litharge) and
peroxide of lead in the proportion of two equivalents of lead oxide (litharge) to
one equivalent of peroxide of lead. The temperature in this case is gradually
increased towards the close of the reaction. Separation of the red lead is effected
by filtration and the product and byeproducts in solution separated as in the
previous instances by fractional crystallization.
•
Having now particularly described and ascertained the nature of our said in-
vention, and in what manner the same is to be performed, we declare that what we
claim is:
1. The preparation of the nitrites of the alkali or alkaline earth metals by the
action of lead sulphide (galena) on their corresponding nitrates preferably in the
presence of alkai with production of plumbates, plumbites, sulphates, and oxides
of lead as byeproducts, substantially as described.
2. The production of litharge from lead sulphide (galena) by the action of
galena on nitrate of soda in the presence of alkali, substantially as described.
3. The production of peroxide of lead from lead sulphide (galena) by the action
of gelena on nitrate of soda in the presence of alkali, substantially as described.
Dated this 25th day of September 1897.
JOHN MCGOUGAN.
ANGUS MCGOUGAN.