Improvements in the Process of Evaporating Silicate of Soda Solutions.
Year: 1894

page_text: Date of Application, 6th Oct., 1894.
Complete Specification Left, 29th June, 1895-Accepted, 3rd Aug., 1895.
PROVISIONAL SPECIFICATION.
Improvements in the Process of Evaporating Silicate of Soda
Solutions.
We, JOSEPH JOHN CROSFIELD and KARL EMIL MARKEL, of Joseph
Crosfield & Sons, Soap Works, Warrington, in the County of Lancaster, do
hereby declare the nature of this invention to be as follows:-
This invention relates to an improvement of the process of evaporating silicate of
soda solutions and our main object is to cheapen the process of evaporation and to
enable silicate of soda solutions to be brought into a solid or semi-solid form,
thereby preventing leakage in hot climates and enabling cheaper packages to he
used. At the same time, the formation of any solid matter which interferes with
the production of a perfectly clear article, is prevented and so au improved article
produced.
Both alkali and neutral silicate of soda having a composition expressed roughly
by the formula Na.Si,O, & Na,SiO, respectively, are brought into the market
in as concentrated a form as possible and hitherto it has not been possible by the
methods so far known, to concentrate solutions of this substance to a greater strength
than 140°-145° Twaddle in the case of the alkaline, & 110°-120° Twaddle in the
case of the neutral. We find that this is due to the fact that silicate of soda being
evaporated in open vessels, causes a skin to be formed at the strength of about
145° Twaddle in the first case and about 100° Twaddle in the second, which skin
prevents further evaporation or further concentration.
Now by our invention, we evaporate silicate of soda solutions in a vacuum instead
of in open vessels, as formerly. By doing this, the skin aforesaid, is not formed
and the evaporation can therefore be carried considerably further, so far indeed that
the concentrated solution is solid, or becomes solid when cooled to ordinary
temperature. Furthermore, by our invention of evaporating in a vacuum, no
dehydrated silicate is formed, which clings to the sides of the vessels, and gives n
cloudy appearance to the finished material, owing to the boiling point under
reduced pressure, being lower.
-Dated this 5th day of October 1801
improvements in the Process of Evaporating Silicate of Soda
Solutions.
We, JOSEPH JOHN CROSFIELD and KARL EMIL MARKEL of Joseph
Crosfield & Sons, Soap Works, Warrington, in the County of Lancaster, do
hereby declare the nature of this invention and in what manner the same is to te
performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to an improvement of the process of evaporating silicate

page_text: I. 1.
of soda solutions and our main object is to cheapen the process of evaporation and
to enable silicate of soda solutions to be brought into a solid or semi-solid form,
thereby preventing leakage in hot climates and enabling cheaper packages to be
used. At the same time, the formation of any solid matter which interferes with
the production of a perfectly clear article, is prevented and so an improved article
produced:
Both alkali and neutral silicate of soda having a composition expressed roughly
by the formula Na,SiO, & Na Si O, respectively, are brought into the market
in solution in as concentrated a form as possible and hitherto it has not been
possible by the methods so far known, to concentrate solutions of this substance to
a greater strength than 140-145° Twaddle in the case of the alkaline, &
110° 120° Twaddle in the case of the neutral silicate of soda. We find that this
is due to the fact that. silicate of soda being evaporated in open vessels, causes a
skin to be formed at the strength of about 145° Twaddle in the first case and
about 100° Twaddle in the second, which skin prevents further evaporation or
further concentration.
Now by our invention, we evaporate silicate of soda solutions in a vacuum instead
of in open vessels, as formerly: By doing this, the skin aforesaid, is not formed
and the evaporation can therefore be carried considerably further, so far indeed that
the concentrated solution is solid, or becomes solid when cooled to: ordinary
temperature. Furthermore, by our invention of evaporating in a vacuum, no
dehydrated silicate is formed, which clings to the sides of the vessels, and gives a
cloudy appearance to the finished material, owing to the boiling point under reduced
pressure, being lower.
Throughout this Specification silicate of soda only is mentioned but it is obvious
that the same process is applicable to the making of the small amount of silicate.of
potash that is mauufactured.
Having now particularly described and ascertained the nature of our said inven-
tion, aud in what manner the same is to be performed, we declare that what we
olaim is
1. The improvement in the process of evaporating silicate of soda solutions
which consists in evaporating them under a vacuum, instead of in open vessels as
formerly.
2. The production of a solution of silicate of soda of 170°-180° Twaddle in the
manner described. .