IMPROVEMENTS IN REMOVING SULPHUR FROM CAUSTIC SODA OR AMMONIA WHEN CONTAINING SULPHIDES
Year: 1873

page_text: LETTERS PATENT to Ernest Smith, of Glasgow, in the County of
Lanark, North Britain, Manufacturing Chemist, for the Invention
of "IMPROVEMENTS IN REMOVING SULPHUR FROM CAUSTIC SODA OR AMMONIA
WHEN CONTAINING SULPHIDES."
Sealed the 21st April 1874, and dated the 3rd November 1873.
PROVISIONAL SPECIFICATION left by the said Ernest Smith at the
Office of the Commissioners of Patents, with his Petition, on the
3rd November 1873.
I, ERNEST SMITH, of Glasgow, in the County of Lanark, North Britain,
Manufacturing Chemist, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN REMOVING SULPHUR FROM CAUSTIC SODA OR AMMONIA
WHEN CONTAINING SULPHIDES," to be as follows :-
-
This Invention has for its object to remove sulphur from caustic soda
or ammonia in a practically complete but yet economical manner.
In carrying out the Invention in the case of soda, the liquor obtained
from black ash is first rendered caustic in the usual way by means of
lime, and after being separated, from the lime, has suspended in it

page_text: granulated zinc, with which it is agitated until all the sulphur has com-
bined with zinc. The zinc that is unacted on is then removed, and the
zinc sulphide settles to the bottom, and after separation can be used for
making sulphate.
In the case of ammonia, the same process is adopted, or a solution of
ammoniacal salt may be put in a still with the lime necessary for
rendering the ammonia caustic, and with a quantity of ferrous sulphate
(known as copperas) corresponding to the sulphur present, whereupon
the caustic ammonia may be directly distilled over, free from sulphur.
For the zinc any metal may be substituted, the sulphide of which is
insoluble in the alkali; or in the case of ammonia any salt or compound
may be used instead of the ferrous sulphate, if the sulphide of the metal
thereof is not decomposable on boiling with lime.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Ernest Smith in the Great Seal Patent Office on 1
the 1st May 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ERNEST
SMITH, of Glasgow, in the County of Lanark, North Britain, Manufac-
turing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 2
Letters Patent, bearing date the Third day of November, in the year
of our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Ernest Smith, Her special licence that I, the
said Ernest Smith, my executors, administrators, and assigns, or such 2
others as I, the said Ernest Smith, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN REMOVING SULPHUR FROM CAUSTIC
SODA OR AMMONIA WHEN CONTAINING SULPHIDES," upon the condition (amongst
others) that I, the said Ernest Smith, my executors or administrators,

page_text: by an instrument in writing under my, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Ernest Smith, do hereby declare the
nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement in writing, that is to say:—
My said Invention has for its object to remove. sulphur from caustic
soda or ammonia, in a practically complete but yet economical manner.
In carrying out my Invention in the case of soda, I take the liquor
obtained from black ash and first render it caustic in the usual way by
means of lime; then after separating the liquor from the lime, I suspend
in it granulated zinc, which may be conveniently done by placing the
zinc in perforated iron boxes, and immersing these boxes in the liquor.
The sulphur in the liquor combines with the zinc, and the liquor is
agitated until all the sulphur in the liquor has become so combined,
which may be ascertained by known tests. The zinc that remains
unacted on is then removed, whilst the zinc sulphide formed is allowed
to settle, and after separation can be used for making zinc sulphate.
The clear caustic liquor is finally concentrated if required to a strength
suitable for sale.
In the case of ammonia, I may adopt the same process as that herein-
before described as applied to caustic soda. I however prefer to proceed as
follows: I put a solution of ammoniacal salt into a still, along with the
lime required for rendering the ammonia caustic, and with a quantity of
ferrous sulphate (known as copperas) sufficient to combine with the
sulphur present. I then distil over the caustic ammonia which is thus
directly obtained free from sulphur.
For the zinc any metal may be substituted, the sulphide of which is
insoluble in the alkali; and in the case of ammonia any salt or compound
may be used instead of the ferrous sulphate, provided that the sulphide
of the metal of such salt or compound is not decomposable on boiling
with lime.

page_text: Having thus particularly described my said Invention, and the
manner of performing the same, I have to state that I do not restrict
myself to the precise details herein-before described, but that what I
believe to be novel and original, and claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,-
1. The removing of sulphur from caustic soda or ammonia by agitating
a solution thereof with zinc or other metal, the sulphide of which is
insoluble in the alkali as herein-before described.
2. The obtaining of caustic ammonia free from sulphur by distilling
a solution of an ammoniacal salt, to which are added lime and ferrous
sulphate or other salt or compound yielding a sulphide not decom-
posable on boiling with lime as herein-before described.
In witness whereof, I, the said Ernest Smith, have hereunto set my
hand and seal, this Thirtieth day of April, in the year of our
Lord One thousand eight hundred and seventy-four.
ERNEST SMITH. (L.S.)