AN IMPROVED MODE OF PREVENTING THE INCRUSTATION OF STEAM BOILERS
Year: 1857

page_text: LETTERS PATENT to Henry Hobbs, of Cambridge Street, Saint Pancras,
in the County of Middlesex, Contractor, and Edward Easton, of The
Grove, Southwark, in the County of Surrey, Engineer, for the Invention
of "AN IMPROVED MODE OF PREVENTING THE INCRUSTATION OF STEAM
BOILERS."
Sealed the 31st July 1857, and dated the 9th May 1857.
PROVISIONAL SPECIFICATION left by the said Henry Hobbs and Edward
Easton at the Office of the Commissioners of Patents, with their Petition,
on the 9th May 1857.
We, HENRY HOBBS, of Cambridge Street, Saint Pancras, in the County
of Middlesex, Contractor, and EDWARD EASTON, of The Grove, Southwark, in
the County of Surrey, Engineer, do hereby declare the nature of the said
Invention for "AN IMPROVED MODE OF PREVENTING THE INCRUSTATION OF STEAM
BOILERS," to be as follows:-
The object of this Invention is to prevent the sediment or calcareous
deposits in steam boilers from forming a hard crust on the bottom and sides
thereof, and also to remove such incrustation when formed. To this end we
employ a solution or paste composed of arsenic and soda, or other alkali,
which compound will enter into chemical combination with the sedimentary
substances introduced into the boiler with the water, and effectually prevent it
from solidifying. We propose to apply this compound, when in the form of a

page_text: liquid, by pumping it into the boiler in. given proportions according to the
quality of water used. But, when in the form of a paste, we lay it on the inner
surface of the sides and bottom of the boiler with a brush after the manner of
applying paint, and if the boiler is already furred, the compound will quickly
combine with the hard calcareous deposit, and loosen and ultimately destroy !
the coating, the portions of which may then be removed by hand, or blown out
of the boiler by the blow-off pipe in the usual way.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Hobbs and Edward Easton in the Great Seal: Patent
Office on the 7th November 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HENRY
HOBBS, of Cambridge Street, Saint Pancras, in the County of Middlesex;
Contractor, and EDWARD EASTON, of The Grove, Southwark; in, the County of
Surrey, Engineer, send greeting...
tv
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of May, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,"
the said Henry. Hobbs and Edward Easton, Her special license that we,
the said Henry Hobbs and Edward Easton, our executors, administrators,
and assigns, or such others as we, the said Henry Hobbs and. Edward Easton,.
our executors; administrators, and assigns, should at any time agree with, and
no others, from time to time and at all times thercafter 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 "AN IMPROVED MODE OF PREVENTING THE
INCRUSTATION OF STEAM BOILERS;" upon the condition (amongst others) that we,i
the said Henry Hobbs and Edward Easton, by an instrument in writing.
under our hands and seals, or under the hand and seal of one of us, 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 toi be filed
in the Great Seal Patent Office within six calendar months next and,imnie..
diately after the date of the said Letters 'Patent. "
NOW KNOW YE, that I, the said Henry Hobbs, on behalf of myself and.
of the said Edward Easton, do hereby declare the nature of our said:
Invention, and in what manner the same is to be performed, to be par-

page_text: ticularly described. and, ascertained in. and by the following statement (that is:
to say):
The chief object of our Invention is to prevent the, calcareous and other;
deposits in steam boilers from: forming.a..hard crust on the bottom and sides
thereof, and thereby deteriorating the heat-absorbing qualities of such boilers.
The Invention has also reference to the removal of such: incrustations: when
formed: To obtain this result we employ a solution or..paste:composed₁'and
applied, in the manner to be presently described; for the purpose of acting:che->
mically on and disentegrating the already formed hard deposit, or of retaining:
the deposit as it falls in a loose granular state. We are well aware that many,
chemical, substances have been proposed from time to time for effecting, by
their presence in the water under evaporation, the removal or prevention of
incrustation, and that some of these have more, or less succeeded.. or totally
failed, according to the chemical nature of the deposit on which they were
designed to act; we do not therefore pretend that our Invention is equally
efficient under all circumstances. As, for the successful. action, the chemical
compound which we employ, the presence in the boiler of some, chemical
property that will ensure the setting up of a chemical action with the
compound may perhaps be requisite to the attainment of the required result.
We have, however, proved by practical experience that our Invention is
eminently applicable to boilers using either, Thames water or sea water.
The chemical compound which we employ consists of arsenious acid (the
white arsenic of commerce) and an alkali, by preference carbonate of soda
(the soda of commerce). These we mix together in equal parts (by weight)
in a copper or other convenient vessel with a small quantity of water, and
keep the same boiling slowly until the arsenic is dissolved. We then cool
down gradually, and the liquid is ready for use. As a precaution against the
inadvertent and improper use of the solution, we prefer to tint by the addition
of indigo or other inexpensive coloring matter. When applying the compound
in a liquid state, we pump it into the steam boiler in given proportions,
according to the quality of the water used. Thus, for example, we find that in
a steam boiler of forty horse power, where Thames water is used, one gallon
per week will suffice to prevent the formation of furr on the bottom of the
boiler. For convenience of transport, it may be convenient to evaporate the
water from the liquid compound until it is reduced to a pasty state. In this
form it may be applied to the inner surface of the bottom and sides of a'
furred boiler by means of a brush, after the manner of laying on paint; the
boiler being then put into use, the compound will be found to decompose
portions of the hard calcareous deposit, and ensure its rapid disengagement

page_text: from the boiler plates. The loose portions may then be removed by hand, or
discharged from the boiler by the blow-off pipe in the usual way. For
removing the deposit which takes place in presence of the compound in the
boiler, the blow-off action will be sufficient, as the deposit will consist merely
of loose granules.
Having now set forth the nature of our Invention of "An improved Mode
of. Preventing the Incrustation of Steam Boilers," and explained the manner
of carrying the same into effect, we wish it to be understood that, under the
above in part recited Letters Patent, we claim, the use of an arsenious alkaline
compound, in the manner and for the purpose above described,
In witness whereof, I, the said Henry Hobbs, have hereunto set my
hand and seal, the Seventh day of November, in the year of our
Lord One thousand eight hundred and fifty-seven.
Witness,
J. W. Moffatt,
66, Chancery Lane.
HENRY HOBBS. (L.S.)