A CONSIDERABLE IMPROVEMENT IN THE PROCESS OF MAKING OF ALLUM, WHEREBY THAT ARTICLE WILL BE PRODUCED, WITHOUT INJURING THE QUALITY, MUCH CHEAPER THAN BY ANY MODE HITHERTO PRACTISED
Year: 1792

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
HERRING ROBINSON, of Whitby, in the County of York, Gentleman, send
greeting.
WHEREAS His most Excellent Majesty King George the Third did,
by His Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Twenty-ninth day of March, in the thirty-second year
of His reign, give and grant unto me, the said James Herring Robinson,
His especial licence that I, the said James Herring Robinson, during the
term of years therein expressed, should and lawfully might use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
my Invention of "A CONSIDERABLE IMPROVEMENT IN THE PROCESS OF MAKING
OF ALLUM, WHEREBY THAT ARTICLE WILL BE PRODUCED, WITHOUT INJURING THE
QUALITY, MUCH CHEAPER THAN BY ANY MODE HITHERTO PRACTISED;" in which
said Letters Patent there is contained a proviso obliging me, the said
James Herring Robinson, by an instrument in writing under my hand and
seal, to cause a particular description of the nature of my said Invention, and
in what manner the same is to be performed, to be inrolled in His Majesty's
High Court of Chancery within one calendar month after the date of the
said recited Letters Patent, as in and by the same (relation being thereunto
had) may more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
James Herring Robinson, do hereby declare that my Invention of an improve-
ment in the process of manufacturing.allum by a new method of, mixing the
alkaline salts, is described in the following account (that is to say) :-
The common process of manufacturing allum has, to the best of my know-
ledge, been conducted in the following manner:-The rock, after being dug
or cut out of its natural bed, is barrowed upon large stacks of wood or other
fuel, which is kindled when properly laden, and more rock added as required;
by such means, a large heap of .rock.is, calcined, and goes by the appellation
of the mine heap.or burnt mine. The rock thus calcined is put into pitts,
and water, or water already impregnated in a small degree from mine, is
poured upon it until it becomes of a sufficient strength for boiling, and is then
called strong liquor. The boilers being supplied with this liquor, and the
loss by evaporation made good by a further supply, are continued boiling
twenty-four hours or thereabouts, untill it is sufficiently concentrated. It now
becomes necessary to mix the alkaline salts or alkaline solution with it, which
has invariably been done to the best of my knowledge in the following way :-
After the alkaline salts are dissolved in so large a quantity of water that the
specific gravity of the solution (or lees as commonly called) is not more
than '06 heavier than common spring water, or five pennyweights, according
to the customary weights used by allum makers, they are run together
with the prepared liga or in the boilers into a cistern or receptacle called the
setlar, where the liquor or mixture in two or three hours time is depurated
by subsidence and precipitation, and leaves a residium or refuse at the bottom
called slam; the mixture is then drawn off from the setlar into other recep-
tacles called coolers, where it remains four days for christalizing; the liquid
part (called muthers) is then let off, the christals of allum taken out, washed
in water, and further depurated or refined by a process called roaching. The
liquor in which the christals of allum were washed, is called washings, and
the. liquor remaining in the casks in which they were roached is called tun
water, the casks being called tuns. Now let us return to the boiler from
which the concentrated liquor was run off. After a manufactory has been
established long enough to have muthers drawn off or scooped out from the
coolers, the boilers are filled up with these (immediately after having been
emptied off the concentrated liquor), and the loss by evaporation continually
made good with strong liquor from the pitts, until in about twenty-four, hours
they are again run off together with the alkaline solution. Now, in this case,
where the boilers were filled up with muthers, the concentrated liquor at the
time of running off is at a much greater weight or too highly inpissated to

page_text: admit of its forming regular christals; in that state the lees or alkaline solution
has therefore. always contained so large a quantity of water to reduce this
highly concentrated liquor to a proper standard for christalizing (the old
practitioners not being acquainted with any other better. method for making
this reduction), as that they have. never in general practice exceeded the
specific gravity before mentioned of 06 heavier than common spring
water. The usual quantity of water used in making the alkaline solution.
was equal to about one half of the quantity of concentrated liquor in the
boilers at the time of running off or drawing off, as usually termed, or: to. one
third of the mixture when drawn off into the setlar; and as this water had to
be evaporated again out from the muthers, it caused an expence of about one
third of all the fuel used at the boiling house besides other attendant expences.
Now my Invention of an improvement in the process of manufacturing
allum has for its object and, principal end. to. abolish the use.of.so large
a proportion of water as has been 'usual in making the .alkaline solution in
any case, and in most cases to do wholly without any, and to. make..the
reduction of the. highly concentrated liquor to a standard. for christalizing
by means of either the strong liquor or washings.which had. to go into the
boilers at all events. The means I make use of are as follows:-First, when
the alkaline salts are clean; pure, and commonly good, I cause. about two
hundredweight to be put into each boilér (an hour or two before the liquor
is drawn off into the setlar), taking the. precaution to put it in. at the back,
and to prevent the otherwise too great effavescence; and in order to reduce
the concentrated liquor to a proper standard for christalizing, I cause a proper
quantity of the strong liquor in common or washings occasionally to run off
with it into the setlar, the rest of the process remaining as has been; usual or
customary. Secondly, when the strong liquor is not too rich of allum,' or not
saturated with it, then I cause about one half of the quantity of alkaline salts
used per diem to be dissolved in the strong liquor, and the other half or one
hundredweight to each boiler is put into the boiling liquor, as in the first case;
the solution of salts in strong liquor is used to make the reduction in this case,
as cómmon strong liquor or washings was in the first; the rest of the process as
usual or customary. Thirdly, when none but very inferior salts can be procured,
such as are foul and cannot safely be put into the boilers for fear of burning.
them out or making them run, and such as would not deposit their hetore-
geneous matters so readily in strong liquor; in such case I cause a saturated
solution of them in water to be made of the specific gravity of 30 or upwards,
and mix this solution, when clear, with as much strong liquor or washings as
will be required to reduce the concentrated liquor in the boilers to a proper

page_text: standard for christalizing; the rest of the process as usual. In this last case
it may require rather more than at the rate of two hundredweight of salts
to each boiler.
To the end that the principle upon which my improvement is grounded
may be thoroughly understood, and that no person may imagine that my
claim and right under these Letters Patent may be eluded by divers .va-
riations which may be made in the foregoing process, without producing any
notable defect in the quantity or quality of allum, and that the art of ma
nufacturing allum upon this new plan may be gathered from this Specification
and perpetuated to the public, I shall add the following observations:-
Instead of using the common lees or solution of alkaline salts in pure water
of the specific gravity of 06 heavier than common spring water, or of 5
pennyweights, according to the customary weights used by allum makers,
their specific gravity may be increased to any given standard short of satu-
ration; but in such case the quantity of lees will be less and will not alone be
sufficient to reduce the concentrated liquor in the boilers to be so low a
standard as is necessary for christalization, therefore you must take a quantity
of strong liquor or of washings in addition to your lees to produce the
desired effect. The alkaline salts may be added to the liquor when in the
setlar, or even when in the coolers, and that either in mass or in solution.
The solution of alkaline salts may be made in tun water, or in washings,
or. in slam water, or even in muthers. The concentrated liquor in the boilers,
when ready for drawing off into the setlar, may be reduced to a proper
standard for christalizing by tun water, by slam water, or by muthers reduced
with water. The reduction of the highly concentrated liquor to a proper stan-
dard for christalization by any of the aforenamed lighter liquid may be made by
first putting any of those liquid into the setlar or into the coolers, and running
the boiling liquor upon it. A smaller proportion of muthers than usual
may be used to the boilers, or even none at all, and in such case there will not
be need for a light liquid to make a reduction of the concentrated liquor, as,
when alkaline salts or solution is added, the mixture may be at a proper
weight for christalizing. In case alkaline salts cannot be procured or
should be too dear, some species of neutral salts may be used, especially
salited mineral alkali or common salt.
In witness whereof, I, the said James Herring Robinson, have here-
unto set my hand and seal, this Twenty-third day of April, in the
year of our Lord One thousand seven hundred and ninety-two.
JAMES HERRING ROBINSON. (L.s.)

page_text: AND BE IT REMEMBERED, that on the said Twenty-third day of April,
in the year above mentioned, the aforesaid James Herring Robinson came
before our said Lord the King in His Chancery, and acknowledged the
Specification aforesaid, and all and every thing therein contained, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute in that case made and provided.
Inrolled the Twenty-seventh day of April, in the year above mentioned.