IMPROVEMENTS IN THE MANUFACTURE AND PURIFICATION OF THE METAL MAGNESIUM." PURIFICATION OF THE METAL MAGNESIUM
Year: 1863

page_text: LETTERS PATENT to Edward Sonstadt, of Loughborough, in the County
of Leicester, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE AND
PURIFICATION OF THE METAL MAGNESIUM."
PURIFICATION OF THE METAL MAGNESIUM."
Sealed the 10th November 1863, and dated the 21st May 1863.
PROVISIONAL SPECIFICATION left by the said Edward Sonstadt at
the Office of the Commissioners of Patents, with his Petition, on the
21st May 1863.
I, EDWARD SONSTADT, of Loughborough, in the County of Leicester, do
hereby declare the nature of the Invention for "IMPROVEMENTS IN THE MANU-
PACTURE AND PURIFICATION OF THE METAL MAGNESIUM," to be as follows:-
This Invention has for its object improvements in the manufacture and
purification of the metal magnesium. In the Specification of a Patent granted
to me, and dated the 8th November 1862, N° 3021, I have described a
process of manufacturing magnesium by decomposing with sodium a material
obtained by evaporating to dryness and igniting a solution of the mixed
chlorides of magnesium and of sodium; I have found that in the preparation
of this material chloride of potassium may be advantageously substituted for
chloride of sodium.
In order to purify metallic magnesium I distil in a peculiar apparatus,
which I will proceed to describe :-It consists of two vessels connected
together by a pipe or passages; these vessels are both capable of being closed
air-tight, and during the process of distillation they are so closed. One of

page_text: these vessels is placed in a furnace and surrounded by the fuel there; in this
vessel the magnesium is contained; the other vessel, which is immediately
below it is fitted into a recess formed for it in the fire-grating or bars of the
furnace, and it projects below. The crude magnesium having been placed in
the upper vessel and the apparatus closed, so that the joints shall be air-tight,
a current of dry hydrogen gas is passed through the two vessels, there being
a small aperture left in each vessel for this purpose. When the whole of the
air has been swept out these apertures are closed by driving in steel plugs,
but there is a small passage left in the plug of the lower vessel, so that when
the apparatus is heated and the gas expands the excess may be able to
escape; this passage can be closed with a wire which is made to fit it nicely
The apparatus being charged and ready the fire is lighted around it, and the
hydrogen as it escapes from the before-mentioned small passage or orifice is
ignited and allowed to burn as long as it will, and the passage or orifice is
then closed by means of the wire. The lower vessel is during the process
kept cool by mopping it externally with water. The vessel containing the
magnesium should be heated to a very bright red, approaching a white heat,
but not higher than the vessel can conveniently bear, and it is maintained at
this heat for a sufficient time, which will be known by the lower vessel
becoming cooler than it was at the commencement of the process, notwith-
standing that the heat of the furnace is maintained. The operation being
complete the apparatus is withdrawn from the furnace and cooled, it is then
taken apart and the magnesium will be found in a more or less solid mass in
the lower vessel.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edward Sonstadt in the Great Seal Patent Office on the
20th November 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
SONSTADT, of Loughborough, in the County of Leicester, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of May, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Edward Sonstadt, Her special licence that I, the said Edward
Sonstadt, my executors, administrators, and assigns, or such others as I, the
said Edward Sonstadt, my executors, administrators, and assigns, should at

page_text: any time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and Jawfully 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 "IMPROVEMENTS IN
THE MANUFACTURE AND PURIFICATION OF THE METAL MAGNESIUM," upon the
condition (amongst others) that I, the said Edward Sonstadt, my executors
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, 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 to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Edward Sonstadt, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:-
This Invention has for its object improvements in the manufacture and
purification of the metal magnesium. In the Specification of a Patent granted
to me, and dated the 8th November 1862 (N° 3021), I have described a
process of manufacturing magnesium by decomposing with sodium a material
obtained by evaporating to dryness and igniting a solution of the mixed
chlorides of magnesium and of sodium. I have found that in the preparation
of this material chloride of potassium may be advantageously substituted for
chloride of sodium.
I take chloride of magnesium obtained in a properly pure state, as is
described in the Specification of my said former Patent, and I add to the
solution thereof chloride of potassium, carefully freed from contamination with
sulphuric acid, as in the former Specification is directed in respect to chloride
of sodium. The process is carried on as before, subject only to the following
observations:-Good results may be obtained by using the potassium salt
anywhere between the limits of one-third of an equivalent of the chloride of
potassium to one equivalent of the chloride of magnesium and one atom of
each salt. There is least waste and least escape of hydrochloric acid gas
during the ignition by using the proportion of atom to atom.
But in some
cases this mixture might be found inconveniently bulky in proportion to the
quantity of magnesium contained in the material. The quantity of sodium to
be used should be adjusted to the quantity of magnesium estimated to be in
the material, using two parts sodium for each one estimated part of mag-
nesium, or rather less sodium than this may be used with advantage.

page_text: In order to purify metallic magnesium I distil in a peculiar apparatus,
which I will proceed to describe:-It consists of two vessels connected
together by a pipe or passages; these vessels are both capable of being closed
air-tight, and during the process of distillation they are so closed. One of
these vessels is placed in a furnace and surrounded by the fuel there; in this
_vessel, the magnesium is contained; the other vessel, which is immediately
below it, is fitted into a recess formed for it in the fire-grating or bars of the
furnace and it projects below. The crude magnesium having been placed in
the upper vessel and the apparatus closed, so that the joints shall be air-tight,
a current of dry hydrogen gas is passed through the two vessels, there being
a small aperture left in each vessel for this purpose. When the whole of the
air has been swept out these apertures are closed by driving in steel plugs,
but there is a small passage left in the plug of the lower vessel, so that when
the apparatus is heated and the gas expands the excess may be able to
escape; this passage can be closed with a wire, which is made to fit it nicely.
The apparatus being charged and ready the fire is lighted around it, and the
hydrogen as it escapes from the before-mentioned small passage or orifice is
ignited and allowed to burn as long it will, and the passage or orifice is then
closed by means of the wire. The lower vessel is during the process kept
cool by mopping it externally with water. The vessel containing the mag-
nesium should be heated to a very bright red approaching a white heat, but
not higher than the vessel can conveniently bear, and it is maintained at this
heat for a sufficient time, which will be known by the lower vessel becoming
cooler than it was at the commencement of the process, notwithstanding that
the heat of the furnace is maintained. The operation being complete the
apparatus is withdrawn from the furnace and cooled, it is then taken apart
and the magnesium will be found in a more or less solid mass in the lower
vessel.
The annexed Drawing shows the form of apparatus which I prefer; it is
made entirely of iron. A is the upper vessel into which the crude magnesium
is placed; B is a cover screwed on to this vessel, and B¹ is a passage in this
cover, capable of being closed by a screw plug; C is a tube passing up within
the vessel A; it is screwed into the bottom thereof, and made perfectly tight
by means of a lock nut D; E is the lower vessel, it has a cover F, which is
screwed tightly on to the bottom of the tube C; the cover F is secured to
the vessel E by lugs, which receive the bolts G of the cross pieces H; I is
the fire-grating or bars.
I have found it convenient in practice to submit the crude magnesium to
two distillations, the first to separate the sodium and fixed impurities, and

page_text: the second to complete the purification. It is convenient to use different
apparatus of slightly different form for the two operations. For the first dis-
tillation the lower vessel E is deep, so as to project a considerable distance
below the fire-bars, and hence remains comparatively cool. The sodium comes
over first and forms a distinct layer, and the magnesium vapour condenses as
it enters the vessel E, and solidifies in drops which adhere together, forming a
porous mass. The sodium is readily separated from this mass by washing it
with water. For the re-distillation the vessel E is made much broader and
shallower, so that, although considerably cooler than the upper vessel A, it
may remain throughout the process at a low red heat; the magnesium is then
obtained in the form of a solid cast cake. If two separate distilling operations
be not resorted to the sodium should be separated by other means before the
distillation. It is not altogether essential that the air should be expelled from
the distilling apparatus by means of hydrogen, but it is very advantageous
so to do.
It will be understood that the peculiarities of the apparatus and process of
distillation of metallic magnesium are that the apparatus is made of iron, and
is closed air-tight during the distilling process; that the air is excluded by
filling the apparatus with hydrogen before the commencement of the dis-
tillation, and that the second vessel or receiver is placed immediately beneath
the fire-bars of the furnace which heats the first vessel, or that which contains
the crude metal, so that this second vessel may, when required, be heated
sufficiently to keep the magnesium which distils over in a fused or liquid
state, and so that the pipe connecting the two vessels may be kept sufficiently
hot to prevent the condensation of magnesium in it.
In witness whereof, I, the said Edward Sonstadt, have hereunto set my
hand and seal, this Nineteenth day of November, in the year of our
Lord One thousand eight hundred and sixty-three.
EDWARD SONSTADT. (L.s.)