A NEW SPECIES OF TIN FOI, CAPABLE OF BEING CRYSTALLIZED IN LARGE, VARIED, AND BEAUTIFUL CRYSTALLIZA- TION
Year: 1818

page_text: BRUNEL'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MARC
ISAMBARD BRUNEL, of Chelsea, in the County of Middlesex, Civil Engineer,
send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by His
Letters Patent under the Great Seal of the United Kingdom of Great Britain
and Ireland, bearing date at Westminster, the Fifth day of December, in the
fifty-ninth year of His reign, give and grant unto me, the said Mare Isambard
Brunel, my exors, admors, and assigns, His especial licence, full power, sole
privilege and authority, that I, the said Marc Isambard Brunel, my exors,
adiñors, and assigns, during the term of years therein mentioned, should and
lawfully might make, use, exercise, and vend, within England, Wales, and the
Town of Berwick-upon-Tweed, my Invention of "A NEW SPECIES OF TIN FOI,
CAPABLE OF BEING CRYSTALLIZED IN LARGE, VARIED, AND BEAUTIFUL CRYSTALLIZA-
TION;" in which said Letters Patent there is contained a proviso, that if I, the
said Marc Isambard Brunel, shall not particularly describe and ascertain
the nature of my said Invention, and in what manner the same is to be
performed, by an instrument in writing under my hand and seal, and cause
the same to be inrolled in His Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said Letters
Patent, that then the said Letters Patent, and all liberties and advantages
whatsoever thereby granted, shall utterly cease, determine, and become void,
as in and by the same, relation being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Marc Isambard Brunel, do hereby declare that the nature of my said Inven-
tion of a new species of tin foil, capable of being crystallized in large,

page_text: varied, and beautiful crystallization, and the manner in which the same is to
be performed, are particularly described and ascertained by the following
description thereof, that is to say::
To convey a correct idea of my Invention, it must be observed, first, that
tin in a state of fusion assumes in cooling a crystalline conformation, but if the
surface is scraped or rubbed, or if the piece obtained from fusion is rolled or
beat, the crystalline conformation is broken, sandy, and confused. The tin foil
commonly known and used in the looking-glass. trade in particular, being pre-
pared by rolling and beating, is incapable of producing a large crystallization.
In order to restore it to that state in which it can assume a crystalline con-
formation, and become capable of being crystallized in large, varied, and
beautiful crystallization, it must previously be melted. The Invention consists,
therefore, in the process and in the means which I employ for the purpose of
melting sheets of tin, and particularly the tin foil, which, in general, is little
more than part of an inch in thickness, and which may be several feet
in surface. The sheet of tin or of tin foil intended to be operated upon is laid.
and spread upon a table or plate of iron, cast or wrought, heated to a tempera-
ture-a few degrees. under that at; which tin-melts. This plate or table is either
of metal, glass, stone, or any other suitable substance. The surface must be.
very smooth and .very flat; great care is to be taken that no air is left, under
the sheet of tin, when it has been laid down perfectly. smooth, and as, close as
it appears on the back of a looking glass. I then apply an additional degree
of heat over the surface of the tin by means of a gas flame, which I use in
preference to any other means of, heating,, because the gas conveyed by means
of flexible pipes renders the flame as manageable as a pencil. I am able, by
that means, to produce with certainty of effect a large, varied, and beautiful.
crystallization. The flame must be applied with great precaution, but practice.
will shew how to moderate that heat and regulate its application.. When the
operation is over, the sheet, assumes a new character, it is then a new, species
of tin foil, which it was my object to obtain; the separation from the plate
or table takes place spontaneously by merely blowing on the surface. of the
foil; the tin being thus. restored to its. natural state, possesses.
the crystalline,
conformation which is necessary to answer my purpose. This crystalline con-
formation is not, however, suitable, until it is elicited by the action of acids, which
are applied according to the process which is practised on tin plates, that is to.
say, take one part, by measure, of sulphuric acid, and dilute it with five parts
of water. Take also one part of nitrous acid of commerce, and dilute it
with an equal bulk of water, and keep each of the mixtures separate. Then
take ten parts of the sulphuric acid, diluted in the manner before stated, and

page_text: mix it with one part of the diluted nitric acid, and then apply this mixed acid
to the surface of the tin foil with a soft brush or a spunge, and repeat the
application of the said mixed acid until the result you expect proves satis-
factory. When this has been done, the foil must be well washed with clean
water and immediately dried. It may then be covered with a varnish or japan,
more or less transparent, colourless or coloured at pleasure. The table or
plate might be heated in an oven or on a stove, or in any other way, but as
the heat must indispensably be to a given degree all over its surface, I have
given the preference to the apparatus described hereafter. This apparatus
consists in a large pan on a trough of cast iron, of such dimensions as to admit
of the plate or table being immersed in it, or being laid over its content.
Under this pan or trough I have one or more fires, with their respective flues
and registers. The trough is filled with a metallic composition, say, tin
and lead, which will fuse and remain fluid at a temperature many degrees
below that at which tin will melt. The plate or table is laid on the fluid
metal, over which it naturally floats and keeps itself in an horizontal position.
Oil, mercury, sand, and other substances might have been used as a medium
for heating the plate or table, but I give the preference to a metallic com-
position, and the greater the body of it in fusion the more regularly the heat
will be diffused and sustained. One or two thermometers applied to this
apparatus will prove very useful to indicate the degrees of heat and to regulate
the same by the aid of the registers.
In witness whereof, I, the said Marc Isambard Brunel, party hereto,
have hereunto set my hand and seal, this Fifth day of June, in the
thousand nicht hundred