IMPROVEMENTS IN PURIFYING TIN ORES, AND SEPARATING ORES OF TIN FROM OTHER MINERALS
Year: 1852

page_text: 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 Eighteenth day of
September, One thousand eight hundred and fifty-two, in the sixteenth year
of Her reign, did for Herself, Her heirs and successors, give and grant unto
me, the said John Michell, my exors, admors and assigns, Her especial licence,
full power, sole privilege and authority, that I, the said John Michell, my
exors, adiñiors, and assigns, or such others as I, the said John Michell, my
exors, adiiors, 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, in the Islands of Jersey, Guernsey, Alderney,
Sark, and Man, and in all Her said Majesty's Colonies and Plantations abroad,
my Invention of "IMPROVEMENTS IN PURIFYING TIN ORES, AND SEPARATING ORES
OF TIN FROM OTHER MINERALS;" in which said Letters Patent is contained a
proviso that 1, the said John Michell, shall cause a particular description of
the nature of my said Invention, and in what manner the same is to be per-
formed, by an instrument in writing vnder my hand and seal, to be inrolled in
Her Majesty's High Court of Chancery within six calendar months next
and immediately after the date of the said in part recited Letters Patent, as

page_text: 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
John Michell, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, are fully described and ascer-
tained in and by the following statement thereof, that is to say :-
My Invention consists in the application of common salt for purifying tin
ores and separating ores of tin from other minerals; and in order that my
Invention may be most fully understood and readily carried into effect, I will
proceed to describe the means pursued by me. I first test samples of the ore
containing tin in order to ascertain what quantity of common salt will be
required for the particular ore about to be treated according to my Invention,
and for this purpose I take two samples (of stamped and washed ore) of eight
ounces each, and with one of these I mix one ounce of common salt, and with
the other I mix two ounces of common salt. These two samples I put into
separate crucibles and expose them to a heat of about 163° of Daniel's
pyrometer during about three quarters of an hour, and throw them into
water, and if on analizing the oxide of tin it is found to be pure where the
one ounce has been used, I know that that proportion will do for the whole,
but if the oxide of tin is not pure, and the oxide of tin in the other quantity is
found to be fully sufficient, then either two, or less than two ounces will be
sufficient; if I think that less will do I try a third sample with less, or I try
three or more samples in the first instance; but a workman after some practice,
with care and observation, will soon be able to judge of the quantity of common
salt required, and in some cases he will be able to do so, even without testing
samples of the ores, as above explained. An excess of common salt renders
the mass inconvenient to stir and separate.
Having determined the quantity of salt to be used, I mix with the ore
(previously stamped and washed) the proper proportion of common salt, and
I then subject the mixture to beat in a reverberatory or other furnace, taking
care that the temperature is as nearly as may be about 163° of Daniell's
pyrometer, because at that heat the oxide of tin will not be acted on by the
salt, which is important, as my object is not to decompose the oxide of tin but
to separate the other metals or minerals mixed with the tin ore by rendering
them when united with the chlorine of the salt soluble in water. And this
temperature is to be raised gradually and maintained for about three or four
hours, keeping the mixture stirred from time to time. The mixture is to be
thrown into water and well washed and the tin ore is to be then smelted in
the ordinary manner. The ores containing tin differ very largely, and some

page_text: may be treated with acid only, as described in the Specification of a former
Patent granted to me; other ores will more readily yield to the process above
described, which is readily ascertained by the means of testing above described,
and some ores not acted on fully by the acid process formerly described by
me or by this process may after being treated by the acid process be treated
with advantage by the process above described.
I would remark that I am aware that ores of tin have before been mixed
with common salt and subjected to a high degree of heat in order to render
the oxide of tin soluble in the manufacture of the stannate of soda, I do not
therefore claim generally to mix ores of tin with common salt and apply heat
thereto; but what I claim is the mode herein described of applying common
salt for purifying tin ores and separating ores of tin from other minerals.
In witness whereof, I, the said John Michell, have hereunto set my hand
and seal this Fourteenth day of March, in the year of our Lord One
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