A MEAN OR METHOD OF EFFECTING CERTAIN PURPOSES OR PROCESSES IN WHICH A TEMPERATURE ABOVE THAT OF BOLLING WATER IS REQUISITE OR DESIRABLE, BY APPLYING THE TEMPERATURE REQUISITE OR DESIRABLE IN THE SAID CERTAIN PROCESSES FOR EFFECTING THE SAID CERTAIN PURPOSES, IN A MANNER NOT HITHERTO EMPLOYED THEREIN
Year: 1816

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BRYAN
DONKIN, of Grange Road, Bermondsey, in the County of Surrey, Engineer,
send greeting.
WHEREAS His present Majesty King George the Third, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Second day of March now last past, did give and grant unto me, the said
Bryan Donkin, His especial licence, full power, sole privilege and authority,
that I, the said Bryan Donkin, my executors, administrators, and assigns, and
such others as I, the said Bryan Donkin, my executors, administrators, or
assigns, should at any time agre with, and no others, from time to time and
at all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, and also in all His Majesty's Colonies and Plan-
tations abroad, my Invention of "A MEAN OR METHOD OF EFFECTING CERTAIN
PURPOSES OR PROCESSES IN WHICH A TEMPERATURE ABOVE THAT OF BOLLING
WATER IS REQUISITE OR DESIRABLE, BY APPLYING THE TEMPERATURE REQUISITE
OR DESIRABLE IN THE SAID CERTAIN PROCESSES FOR EFFECTING THE SAID CERTAIN
PURPOSES, IN A MANNER NOT HITHERTO EMPLOYED THEREIN;" in which said
Letters Patent there is contained a proviso, obliging me, the said Bryan
Donkin, by an instrument in writing under my hand and seal, particularly to
describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, and to cause the same to be inrolled in His
Majesty's High Court of Chancery within two calendar months next and

page_text: immediately after the date of the said recited Letters Patent, as in and
by the said recited Letters Patent, reference being thereunto had, will more
fully and at large appear.
NOW KNOW YE, that I, the said Bryan Donkin, in compliance with tho
said proviso, do hereby describe and ascertain the nature of my said Inven-
tion and the manner in which the same is to be performed, as follows, that is
to say:-
To avoid those langers to which workmen are exposed in situations where
steam of high temperature is employed as a medium for transmitting heat to
evaporating vessels, or for any other purpose, and where the steam so employed
has hitherto been kept to its temperature by a safety valve loaded to tho
pressure or expansive power or force of steam answerable to the temperaturo
required, I have contrived a way or method or means for applying the steam
of that temperature which the nature of the process may require, without the
steam being of the pressure or expansive power, which in the common
methods of using it, answers to or corresponds with the temperature.
And this I effect in the following manner, but subject to such modifica
tions as circumstances would point out to every prudent and intelligent
operator, according to the nature of the process to which the said Inven-
tion may be applied; that is, instead of admitting steam directly from
the boiler in which it is generated into the receptacle or case, or other
apparatus or contrivance for bringing the steam into contact with the
evaporating vessel in such a manner that the said receptacle or case becomes
a part of the boiler, or a mere reservoir of steam of the temperature and con-
sequent expansive power of steam brought to a high temperature by being
confined under a given weight; while the boiler continues to be urged by
heat, I raise the steam in my boiler to only two hundred and twelve degrees,
or a few degrees more; and afterwards apply heat to it in its passage to the
said receptacle or case, to bring it to the required temperature in an expanded
state, and consequently in a state of diminished pressure, or without having
a pressure greater than can be balanced by the common weight of the
atmosphere; and the way or method which I employ to apply heat to the
steam after it is generated in any close boiler, is, by conveying it into a vessel,
between the boiler and the said receptacle or case, there to be heated by a fire
applied to the said intermediate vessel, or by applying fire to the tube or pipo.
employed to transmit the steam to the said receptacle or case; and further,
to keep the heated and expanded steam under proper management, as to
temperature and pressure, I attach safety valves to the case or receptacle,
which can be loaded to any degree, which shall prevent the possibility of any

page_text: dangerous accident. Such is the method which I employ to apply the heat of
steam of high temperature with perfect safety to vessels employed for evapora-
tion, or for purposes requiring a higher temperature than that of boiling water,
or two hundred and twelve degrees. By my said Invention is also applicable
to processes where evaporation is required in a different, and for some purposes
a more beneficial manner, which I shall now describe; I must here premise
that any volume of common steam raised to any given higher temperature, and
allowed to expand itself, contains in its expanded form, and can only contain its
original quantity of water; and that consequently such expanded steam, if
brought into circumstances in which it can take up a fresh quantity of water,
will take it up and convert it into steam of some lower temperature; and if
under no restraint, and at the same time furnished with a proper supply of
heat, that the result will be steam of two hundred and twelve degrees. Taking
advantage of this fact, instead of applying the heated steam as hitherto
practised to the outside of the vessel containing the matter to be evaporated, I
contrive to apply steam of high temperature, heated as above described,
directly to the matter itself; and to facilitate the evaporation, I divide the
matter by any suitable mechanical means so as to expose to the action of the
passing and comparatively dry steam as much surface as possible; and I find
that this is best effected by any mechanical means calculated to raise the
matter under process, and then to cause it to descend in a shower or showers.
From what I have just stated, it will be easily conceived that if the
steam from the boiler heated and expanded before it reaches the vessel con-
taining the matter to be evaporated, then pass through the said vessel and
through the shower of evaporable matter, the surface of every drop will be
exposed to the action of the said comparatively dry steam, and will give off a
portion of its water, so that the evaporation of the whole to the required
degree will be much more speedily accomplished than by any process hitherto
in use.
It must also be obvious that the contact of a large surface of the
evaporable liquid with the expanded steam, may be effected by directing the
expanded steam into the body of the liquid whence rising in bubbles to the
surface, the said bubbles of steam being each in their whole surface in contact
with the liquid, will imbibe and carry off with them an additional quantity of
water. The said certain purposes or processes to which my said Invention is
applicable are the ovaporating of sugar, of common salt, alum, and other
saline solutions, of syrups, of extracts, and generally of all matters requiring to
be brought to a more concentrated state, and which cannot be injured by being
brought in contact with such steam; also the heating, annealing, and soften-
ing of metals; also baking of bread and biscuits. I do not rest my Invention

page_text: on the form or forms of the apparatus, which must be varied according to the
particular purpose to which my said Invention may be applied; nor can any
competent mechanist who may make himself acquainted with the particulars
above specified, be at any loss in adapting or modifying such apparatus as is in
common use, or in constructing apparatus adapted to the requisites which have
been described.
In witness whereof, I, the said Bryan Donkin, have hereunto set my
hand and seal, the First day of May, in the year of our Lord
One thousand eight hundred and sixteen.