IMPROVEMENTS IN THE PREPARATION OF MATERIALS TO BE USED IN THE PURIFICATION OF GAS FOR ILLUMINATION
Year: 1863

page_text: LETTERS PATENT to Alexander Angus Croll, of Coleman Street, in the
City of London, Engineer, for the Invention of "IMPROVEMENTS IN THE
PREPARATION OF MATERIALS TO BE USED IN THE PURIFICATION OF GAS FOR
ILLUMINATION."
Sealed the 29th December 1863, and dated the 2nd July 1868.
PROVISIONAL SPECIFICATION left by the said Alexander Angus Croll at
the Office of the Commissioners of Patents, with his Petition, on the.
2nd July 1863.
I, ALEXANDER ANGUS CROLL, of Coleman Street; in the City of London,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE PREPARATION OF MATERIALS TO BE USED IN THE PURIFICATION OF GAS
FOR ILLUMINATION," to be as follows:--
The improvements relate to combining neutral salts, or salts as nearly
neutral as convenient, in a concentrated form and at a high temperature, with
wood sawdust, breeze, spent tan, or other slightly absorbent or cellular matter,
and employing such mixture, after it has been allowed to cool, in purifying
apparatus for the purification of gas. When employing for this purpose
sulphate of alumina, I prefer to take it at a specific gravity of about 90°
(Twaddel), and as nearly neutral as may be conveniently obtained in the
process of manufacture, and at a temperature of about 230°. Fahrenheit, and
to combine six parts thereof by weight with one part of dry wood sawdust.
This combination, when well mixed and allowed to cool down to the tempera-
ture of the atmosphere, I apply in the purifying apparatus.
A suitable mixture may be obtained by combining about 7 parts by weight

page_text: of sulphuric acid (containing 80 per cent. of oil of vitriol), 6 parts finely
divided and roasted china clay, and 2 parts of dry wood sawdust; but the
proportions given may be varied.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Angus Croll in the Great Seal Patent Office
on the 2nd January 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
ANGUS CROLL, of Coleman Street, in the City of London, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of July, in the year of our Lord One
thousand eight hundred and sixty-three, in the twenty-seventh year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alexander Angus Croll, Her special licence that I, the said Alexander Angus
Croll, my executors, administrators, and assigns, or such others as I, the said
Alexander Angus Croll, 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 "IMPROVE-
MENTS IN THE PREPARATION OF MATERIALS TO BE USED IN THE PURIFICATION OF GAS
FOR ILLUMINATION," upon the condition (amongst others) that I, the said
Alexander Angus Croll, my executors or administrators, 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.
.
.
a
NOW KNOW YE, that I, the said Alexander Angus Croll, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
The improvements relate to combining neutral salts, or salts as nearly neutral
as convenient, with wood sawdust or other slightly absorbent or cellular matter,
such salts being in a concentrated form, obtained by evaporation thereof at a
bigh temperature, and the combination with the other matters being effected

page_text: generally when the salt is at. such high temperature, and employing such
mixture, after it has been allowed to cool, in purifying apparatus for the purifi-
cation of gas. In carrying out my improvements the salts I employ are the
sulphate of alumina, the chloride or sulphate of zinc, or the chloride or
sulphate of manganese, or the chloride or sulphate of iron. For the purpose
of obtaining a mixture which shall remain throughout as much as possible free
and open to the action of the gas until saturation thereof, and also for the
purpose of obtaining valuable residual products in the most concentrated form,
I prefer when employing sulphate of alumina to take it at a specific gravity of
about 90° (Twaddle), and as nearly neutral as it can be conveniently obtained
in the process of manufacture, and at a temperature of about 230° (Fahrenheit),
and I combine it in that state with dry wood sawdust, or with other slightly
'absorbent or cellular matter, but I prefer the combination to be with wood
sawdust, and in the proportion of about five parts by weight of such alumina
with one part by weight of dry wood sawdust. When employing the chloride
or the sulphate of manganese, I first evaporate either of them till it becomes
semi-fluid, and until. the temperature thereof. has attained about, say, 230°
(Fahrenheit), and is of a specific gravity of, say, about 120° (Twaddle), when it
is to be mixed with dry wood sawdust or with other slightly absorbent or cellular
matter, but I prefer generally the combination to be with the wood sawdust,
and in that case I find about five parts by weight of the manganese to one part
by weight of the wood sawdust answers well. I also prefer to add a small
quantity of pounded chalk to the salt of manganese previous to its admixture
with the sawdust, in order to neutralize any free acid which may still exist in
such salt; such neutrality is most desirable when the chlorides of any of the
salts referred to are employed. Combinations such as referred to, when well
mixed and allowed to cool down to the temperature of the atmosphere, I reduce
where necessary, so that they may be used in a dry, or comparatively dry, free,
and open state, and in that state placed in purifying apparatus, such as that
generally used when purifying gas by dry lime or oxide of iron, and I operate
upon the gas by these means after condensation thereof and before the removal
therefrom of sulphuretted hydrogen, which I prefer to remove by a subsequent
process.
A suitable purifying mixture may also be obtained by combining sulphuric
acid, at a temperature of about 230° (Fahrenheit), with roasted china clay and
wood sawdust or other slightly absorbent or cellular matter, which I well stir
during the process of mixing, and I find that about seven parts by weight of
sulphuric acid (containing 80 per cent. of oil of vitriol), six parts of finely-
divided and roasted china clay, and two parts of dry wood sawdust answer

page_text: well; but the proportions given may be varied. When employing a chloride
or & sulphate of zinc, or a chloride or a sulphate of iron, the neutrality of such
salts may readily be obtained by the introduction of metallic ziņo or turnings,
or other reduced portions of iron, as the case may be, to the solutions. In the
case of the chloride of zinc or the chloride of iron, the evaporation may be
continued until the temperature arrives at about 300° (Fahrenheit). The
evaporation of the sulphate of zinc and of the sulphate of iron need not be
continued to above a temperature of about 230° (Fahrenheit), but about
double the quantity of sawdust will be required with the sulphate or chloride
of zinc, or chloride of iron, to what is required for the salts of manganese..
When employing a chloride of zinc or of manganese or of iron, a beneficial
result may also be obtained by their use, after the concentration and treatment
thereof. referred to, by mixing either of such chlorides with the sawdust after
being allowed to cool, but then the evaporation may be carried on until the
temperature rises, say, about 20°. (Fahrenheit) higher than when the sawdust is
mixed at a high temperature. As both the chloride of zinc and the chloride
of iron are highly deliquescent. salts, it will be desirable, after the preparation
and mixture of either of them. with the sawdust is complete, that if not imme-
diately used in the purifiers they be kept protected from the action of a moist
atmosphere. In the evaporation of the salts referred to, surface heat will be
found the best adapted to the purpose.
:
Having thus described. the .nature of, my Invention, and means which I
adopt in carrying the same into effect, I would have it understood that I do
not confine myself to the precise details referred to, as these may be varied;
but what I do claim is, the combining the neutral salts referred to (or as nearly
neutral as convenient) with wood sawdust or other slightly absorbent or cellular
matter, and employing such mixture in purifying apparatus for the purification
of gas, substantially as explained.
In witness whereof, I, the said Alexander Angus Croll, have hereunto
set my hand and seal, this Second day of January, in the year of
our Lord One thousand eight hundred and sixty-four.
.
A. ANGUSCROLL. (L.B.)
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