CERTAIN IMPROVEMENTS IN VACUUM PANS FOR THE EVAPORATION AND CRYSTALLIZATION OF SACCHARINE OR OTHER SOLUTIONS;
Year: 1852

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
JOSEPH WALKER, Junior, of Wolverhampton, in the County of Stafford,
Merchant, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-fifth day of May
(One thousand eight hundred and fifty-two), in the fifteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said Joseph Walker, my exors, admors, and assigns, Her especial licence, full
power, sole privilege and authority, that 1, .the said Joseph Walker, my exors,
adñmors, and assigns, or such others as I, the said Joseph Walker, my exors,
admors, or assigns, should at any time agree 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 in the Islands of Jersey, Guernsey, Alderney,
Sark, and Man, and also in all Her said Majesty's Colonies and Plantations
abroad, the Invention of "CERTAIN IMPROVEMENTS IN VACUUM PANS FOR THE
EVAPORATION AND CRYSTALLIZATION OF SACCHARINE OR OTHER SOLUTIONS;"
municated to me from abroad; in which said Letters Patent is contained a
proviso that I, the said Joseph Walker, shall cause a particular description of
the nature of the said Invention, and in what manner the same is to be
performed, by an instrument in writing under my hand and seal, to be inrolled
in Her said Majesty's High Court of Chancery within six months next

page_text: and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Joseph Walker, do hereby declare that the nature of the said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had
to the Drawing hereunto annexed, and to the figures and letters marked
thereon, that is to say:-
The said improvements consist in, first, such a combination of rectilinear
tubes that their collective surfaces may be made to bear any desired pro-
portion to the contents of the vacuum pan for which they may be intended, or,
in other words, such that the amount of heated surface in a pan of any
given size may be infinitely increased beyond that which can be obtained
by any of the methods as now used.
Second, the manner of arranging the tubes so that their surfaces exposed to
the liquid to be evaporated, and liable to calcarious or other incrustations,
may be easily accessible for the purposes of cleaning or repairing.
Third, such an arrangement of the interior of the vacuum pan as will afford
certain spaces where there can be no ebullition or other violent commotion of
the contents of the pan, thus ensuring a more perfect crystallization than has
heretofore been obtained.
Two of the most convenient forms combining these improvements are shewn
in the annexed Drawing. A, A, Figure 1, shews the exterior of a vacuum
pan formed in three sections, bottom, body, and top; B, B, section of a steam
drum traversed parallel to its axis by metallic tubes whose extremities are
secured in holes made in the heads in any of the modes in use for securing the
flues of locomotive boilers; C, C, a cylinder of metallic sheets dividing the
space between the drum and exterior of the pan, so that each division may have
free communication with the spaces above and below the drum; D, pipe for
the admission of steam to the drum; E, pipe for discharging the water formed
by condensation of the steam.
In Figure 2, formed by the addition of an upper and lower chamber
directly to the steam drum, pipes to communicate the two chambers may be
added, as represented by G, and a large tube in the centre or other convenient
part of the steam drum, with a concentric cylinder C, C, will facilitate the
circulation of the contents of the pan, as shewn by the arrows; one or other,
or both may be used, as circumstances may require.
The operation of the vacuum pan is as follows:-Suppose the liquid to be

page_text: evaporated already in the pan covering the outer drum, and some two or three
inches more steam admitted to the interior of the drum, and the vacuum
established by connection with pneumatic pumps, the transmission of the
latent heat of the steam through the drum and tubes to the liquid contents of
the pan will cause ebullition and an ascending current through the tubes and
space between the drum and the cylinder C, C, a quietly descending one
through the space between the cylinder and the exterior of the pan. While
passing this space, and while in the lower chamber, the particles are not in
motion among themselves, and crystallization proceeds rapidly so soon as the
solution shall have reached the point of saturation. This process is also facili-
tated by the successive and rapid changes of temperature produced by contact
alternately with the heated surfaces of the drum and tubes, and the colder ones
of the exteriors of the body and bottom of the pan.
In witness whereof, I, the said Joseph Walker, have hereunto set my
hand and seal, this Twenty-seventh day of July, in the year of our
Lord One thousand eight hundred and fifty-two.