IMPROVEMENTS IN THE MANUFACTURE OF THE METAL MAGNESIUM
Year: 1862

page_text: LETTERS PATENT to Edward Sonstadt, of No. 3, Stewart Place, Alfred
Street South, Nottingham, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF THE METAL MAGNESIUM."
Sealed the 24th April 1863, and dated the 8th November. 1862.
PROVISIONAL SPECIFICATION left by the said Edward Sonstadt at
the Office of the Commissioners of Patents, with his Petition, on the
8th November 1862.
I, EDWARD SONSTADT, of No. 3, Stewart Place, Alfred Street South, Not-
tingham, do hereby declare the nature of the Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF THE METAL MAGNESIUM," to be as follows:-
This Invention has for its object improvements in the manufacture of the
metal magnesium. For this purpose I proceed in the first place to prepare
pure magnesia, for I have found the magnesia of commerce to contain so
much sulphur as to be unsuitable for my purpose. I obtain pure magnesia
conveniently by precipitating Epsom salts with soda or carbonate of soda. I
allow the precipitate to subside, and decant off the water; I then wash the
precipitate repeatedly in hot or boiling water, and dry it between each
washing either by strong pressure or by a centrifugal machine; these alternate
washings and drying I repeat until the wash water shows no precipitate with
chloride of barium. The drying processes are practically essential to the
purification of the magnesia. The pure magnesia thus obtained I dissolve in

page_text: hydrochloric acid, and I add to the solution chloride of sodium. The mixed
solution is evaporated to dryness, or nearly so, and is then slowly heated to
redness; this should be done in a crucible, into the composition of which silica
does not enter, otherwise this material will be taken up by the mixed salts,
and will act prejudicially on the result. The crucible should be loosely
covered. In this manner I obtain a mixture which is anhydrous, and can be
readily treated to obtain magnesium, and this metal may be obtained from it
by means of electricity; I however prefer to treat it by means of sodium. I
place the material together with sodium in an iron crucible or vessel, which
should be quite clean and free from any oxide of iron. The crucible or vessel
which is kept covered is heated to a bright red heat, and the reduction is
effected. When the crucible or vessel is cool the metal is removed; it is not
however quite pure, as it contains metallic sodium, it being desirable in car-
rying out the process to employ an excess of this material; the magnesium
also is not entirely free from the flux. I separate the sodium by fusing the
metal with anhydrous chloride of magnesium, a material which I prepare by
passing hydrochloric acid gas over the hydrated chloride, kept in a state of
fusion by heat. The flux I separate thoroughly from the metal by fusing a
considerable quantity of metal in an iron crucible, from which air is excluded,
by coal gas or other gas; the metal is kept standing in a fused state for a
considerable time, and will then separate from the flux. In consequence of
the difference of specific gravity, I would remark that it is important that a
clean iron vessel should be used for the reduction of the metal magnesium,
as all other ordinary crucibles are unsuited for the purpose. The metal
magnesium is suitable for use as a substitute for silver and for other purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edward Sonstadt in the Great Seal Patent Office on the
8th May 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
SONSTADT, of No. 3, Stewart Place, Alfred Street South, Nottingham, send 8
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighth day of November, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto 3
me, the said Edward Sonstadt, Her special licence that I, the said Edward

page_text: Sonstadt, my executors, administrators, and assigns, or such others as I,.
the said Edward Sonstadt, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at
all times thereafter during the term therein expressed, should and lawfully
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 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 :-
My improvements in the manufacture of the metal magnesium relate,
firstly, to the manner of preparing magnesia or its carbonate so that it may be
in a suitable state for the obtainment from it of magnesium by the hereafter
described process; secondly, to the preparation of an anhydrous, compound.
containing magnesium, chlorine, and sodium, from which magnesium may*
readily be obtained either by electrolysis of the fused material, or by its reaction
with sodium; thirdly, to the use of iron vessels in which to effect. the reduction.
of magnesium from the said material by means of sodium; and, fourthly, to
the preparation of anhydrous chloride of magnesium, and the use thereof for
the separation of sodium from metallic magnesium.
In the first place I proceed to prepare pure magnesia, for I have found the
magnesia of commerce to contain so much sulphur (in the form of sulphatic
salts) as to be unsuitable for my purpose. I obtain magnesia (or its carbo-
nate) conveniently by precipitating Epsom salts with soda or carbonate of
soda. I allow the precipitate to subside, and decant off the water; I then
wash the precipitate repeatedly in hot or boiling water, and dry it between
each washing either by strong pressure or by a centrifugal machine; these
alternate washings and dryings I repeat until the wash water shews no pre-
cipitate with solution of chloride of barium (which has been acidulated with
nitric acid). The drying processes are practically essential to the purification
of the magnesia. The pure magnesia thus obtained I dissolve in hydrochloric

page_text: acid, and I add to the solution chloride of sodium. Or a suitable chloride of
magnesium may be obtained from the mother-liquors of sea water, which after
precipitation of sulphates by chloride of barium and of calcium, and excess of
barium by just and only just sufficient carbonate of soda or of potash, fur-
nishes at once a solution of chloride of magnesium, which may be used for
production of the metal. It would even be possible to carry the concentration
of the mother liquors of sea water just to that point at which they would
contain the chlorides of magnesium and of sodium in suitable proportion to
form the material in question. The presence of chloride of potassium in the
mother liquors would be no disadvantage, neither would the presence of
alkaline iodides and bromides be injurious.
I do not recommend the employment of commercial magnesia as ordinarily
sold as a source of the metal. The best samples of magnesia that I have
been able to purchase contain a considerable quantity of sulphates, which I
have not found it commercially practicable to separate. The most prolonged
washing with boiling water is totally ineffectual in separating such sulphates.
Nevertheless commercial magnesia may be used, though not to advantage,
for the production of magnesium, and in this case I proceed as follows:-The
magnesia (or its carbonate,) is taken up by undiluted or slightly diluted
bydrochloric acid (free from sulphuric acid) of the usual strength, that is to
say, of about 1.152 sp. gr. slowly poured upon it, the acid being added
very slightly in excess; chloride of barium is then added (in solution)
in sufficient quantity to _precipitate the sulphuric acid. After subsidence
the liquor is decanted and boiled upon bicarbonate of soda or of potash
added in sufficient quantity to neutralize the excess of acid and to pre-
cipitate the barium. Carbonate of soda or of potash may be used instead
of the bicarbonates, but the latter are preferable as their use is attended by
less loss of magnesium, which always falls in considerable quantity with
the barium.
It is impossible by this method to completely separate the barium from the
solution, but I have not found these traces of barium to in the least injure
the product or purity of the magnesium obtained by a subsequent process.
For a reason which will be given under, I avoid, whenever practicable,
the use of ammoniacal salts in every stage of the preparation of the
"material."
After boiling the solution, as described, over the carbonate or bicarbonate
of soda or of potash for about 20 minutes, and then filtering or decantation,
it will be ready for the addition of chloride of sodium, and for the evaporation
and ignition subsequently more particularly described. I however in all

page_text: cases in which cloride of magnesium cannot be obtained from mother liquors
of sea water much prefer to make it from magnesia or carbonate of magnesia
obtained as already described, and which process forms an important feature
of my Invention. To the magnesia thus obtained I add hydrochloric acid,
(free from sulphuric acid) in such proportions that a small quantity of mag-
nesia shall remain undissolved. After boiling, the solution is filtered or de-
canted from the precipitate and portion remaining undissolved. I then add
to the solution chloride of sodium in such quantity that for every pound of acid
used of sp. gr. 1.152 I use 0.55 lbs. of chloride of sodium. I do not confine
myself to this proportion, which is about that of equal atoms of the two salts,
but greatly prefer it to any other proportion. When working mother
liquors the chloride of sodium is employed in similar quantity. The
chloride of sodium may be added to the concentrated solution of chloride of
magnesium in the solid state, and evaporated to dryness, in, by preference, a
silver dish. This dried material is then placed in a platinum crucible loosely
covered and heated to full redness. When it enters into tranquil fusion the
operation is complete, and the fused mass may be poured out on to a clean cold
iron plate, or it may become cold in the crucible, when it will fall out on
inverting and shaking the crucible. The substance thus formed I call techni-
cally "material," and do not call it a double chloride, as I am doubtful as to
its precise chemical constitution. This "material" if not immediately used
must be put into and kept in a perfectly dry vessel which is secured against
the access of moist air, as the material is slightly deliquescent, and a very little
moisture represents the loss of a large quantity of magnesium in the subse-
quent process. If the material after being well fused in the platinum crucible,
as described, be poured off, a portion which remains thick and is settled at the
bottom, should be left in the crucible to be separately taken out and kept
apart from the "material" if it be desired for the magnesium to be obtained
as pure as possible. If the material be not poured out of the crucible, but
allowed to cool within it, the mass will separate readily into two portions, one,
the upper portion, a white and somewhat translucent mass, the other, the
under portion, is of a greyish dark color, and shews evidence of having been
but imperfectly fused.
When magnesia prepared according to the process of precipitating
Epsom salts, and of washing, as I have already described, has been used for
the preparation of the "material;" this dark portion is insignificant in quantity,
and the same is the case when chloride of magnesium obtained from the
mother liquor of sea water is employed, but when the magnesia of commerce
has been used, even although purified as I direct, the proportion of dark matter

page_text: solution of yellow
is considerable. This dark matter is very similar to the dark matter obtained
when chloride of magnesium is obtained by the method usually practised by
chemists, namely, by evaporating and igniting a mixture of the solutions of
chlorides of magnesium and of ammonium. The French chemists call it the
carcasse, and regard it as consisting chiefly of magnesia formed by the decom-
position of the water in the hydrated chloride during the process of ignition.
This carcasse contains however besides magnesia and intermixed chlorides
a péculiar substance, which is, so far as I know, as yet unrecognized by
.chemists. It simulates iron in many of its reactions. Like iron, its acid,
peroxide, and perchloride solutions give a blue with
prussiate of potash, but unlike in the case of iron this blue is unalterable or
changes only to purple when not quite pure on addition of ever so large an
excess of ammonia. The lower oxide or chloride solution of the new element
behaves also like iron in giving a blue with red prussiate of potash, which blue
however unlike that from iron is unchanged by excess of ammonia. Other
reactions of the new substance are exceedingly like those of iron, but when
its precipitate by an alkali is ignited it is reduced to a dark spongy mass
before the blow pipe on charcoal with very great difficulty. This mass does
-not fuse and is not in the least magnetic. It is unnecessary to give further
particulars respecting this element here, but it is necessary to point out that
magnesium is always associated with this element, which has undoubtedly
been hitherto mistaken for iron, however prepared, the new element may be
separated by distillation of the magnesium, and besides this I know of no
other effectual practical method. Even when only the white portion of
material is used for the production of magnesium the metal still contains
traces of the new element, which for convenience of naming and provisionally,
I call X. The material made when the magnesia made as I recommend
is used is very much freer from X as well as from sulphuric acid than when
the best magnesia of commerce is employed.
I have put much stress upon the importance of separating sulphuric acid
from the chloride of magnesium used in the preparation of the "material." It
is equally important that the chloride of sodium used in the process should
likewise be freed from sulphuric acid. I recommend. for this purpose the
following process:-Common salt as it occurs in commerce is dissolved in
water. I prefer to use "condensed" water as constantly made where steam
engines are at work. The solution is treated with a sufficient quantity of solution
of chloride of barium to precipitate all the sulphuric acid. The excess of
barium is precipitated by carbonate of soda (I prefer to boil at this point) in
excess of the barium to be precipitated. After filtration, or better, decantation

page_text: from the precipitate, the solution is neutralized by hydrochloric acid free from
sulphuric acid. I have not found the other foreign substances contained in
common salt at all prejudicial, so that the solution thus obtained is fit for
immediate use.
The reason why sulphuric acid must be so carefully separated from the
materials employed in the manufacture of magnesium is not because magnesium
has a strong affinity for sulphur which it decidedly has not, but because any
sulphates present in the material are reduced to sulphides during the reaction
with sodium. The oxygen thus liberated appears to divide itself between free
sodium and nascent magnesium forming oxides with both. It thus happens
that infusible magnesia is formed along with the reduced metal and effectually
prevents the latter fusing together so as to form in lumps. If more than mere
traces of sulphates be present in the material from which magnesium is reduced,
it will usually be found that the metal is dispersed in very minute powder or
globules throughout the mass, whereas if the material be free from sulphates,
and otherwise properly prepared according to the directions given above, the
reduced magnesium runs, at least in part, into globules of considerable size.
With respect to the running of the metal together in globules or lumps it
remains to be observed that the freer the "material" is from X, the more
completely does this happen.
As already stated, I prefer to use no ammoniacal salts in the course of the
preparation of the material from which the magnesium is ultimately obtained.
I would add, that no substance containing nitrogen should be used.
Magnesium exhibits even in its compounds a powerful affinity for nitrogen
compounds, so that I do not think it can be on a practical scale completely
freed even from ammoniacal salts by howsoever prolonged ignition. A large
portion of magnesia is carried away perhaps partly mechanically, but certainly
partly in chemical combination when magnesia or chloride of magnesium is
ignited with chloride of ammonium. Nor can the remaining chloride of
magnesium be obtained so free from ammonium as not to afford traces of the
usual ammoniacal precipitate when its solution is tested with the bichloride of
platinum. But when the material from which magnesium is to be obtained
contains ammonium, in whatever state of combination, the magnesium obtained
from it invariably contains nitrogen, the presence of which causes the mag-
nesium to have a yellowish color, and to tarnish rapidly in the atmosphere.
In order to obtain magnesium from the "material," I place the latter with
sodium in an iron crucible or vessel closed with an iron cover, and heat to full
.redness. The cover should not be removed from the crucible until the crucible
is nearly cold.. The mass within the crucible may usually be shaken out, or if

page_text: necessary it may be washed out by water. The salts contained in the mass
may be washed away by water, when magnesium, more or less pure and con-
glomerate according to the purity or impurity of the "material" used, remains.
The washing should be effected as rapidly as may be, especially when impure
material has been used. The magnesium should be immediately dried by
a gentle heat not much exceeding 100° centigrade. If inclining to be
pulverulent, the magnesium should not be heaped up while moist, but should
be spread out thinly and rapidly dried, otherwise, if in quantity, it might heat
strongly, or perhaps ignite. This remark applies to impure or badly prepared
magnesium. I recommend moist pulverulent magnesium be placed upon
bibulous paper, or porous slab, or some other substance capable of quickly
absorbing moisture before it is dried by heat. The proportion of sodium to
material that I prefer to employ is about one part of the former to five of the
latter; but the proportion of sodium may be slightly increased or considerably
diminished. If much increased the excess of sodium burns explosively when
the cold fused mass is washed with water, if much less be used the yield of
magnesium is diminished. When the carcasse already described is used as
part of the material rather more sodium may be employed, also if the material
has been so strongly ignited during its preparation as to have volatilized away
any considerable quantity of chloride of sodium, I find the best result to be
obtained when the material is placed in the crucible coarsely powdered.
There should be a layer of the material at the bottom of the crucible, then the
greater part of the sodium in large pieces, and then the crucible should be
filled up with the remainder of the sodium in smaller pieces, and with the rest
of the "material." The crucible should be perfectly free from rust, and the
cover should have an inside flange so as to fit closely, but it need not be
fastened down. The crucible should be quickly heated up to but not beyond
full redness. If the heat be raised too high, magnesium vapour forces its way
beside the cover and burns brilliantly in the air. It it not necessary nor
desirable that the heat should be continued for more than about half an hour
after the whole crucible with its cover has become red hot.
I have never
found the iron vessel in which the reaction is effected to be at all acted upon
interiorly when the cover fitted properly and did not become shifted during the
process; if, however, through bad management, air gain admittance, the iron
becomes attacked so far and so far only as air has penetrated. I never
found the magnesium formed in iron vessels to have taken up any trace of
iron from the vessel unless in case of access of air, or when the heat has been
excessively elevated. With moderate care, no such accident can well happen.
The same iron vessel may be used repeatedly, time after time, without par-

page_text: ticular cleaning it no water or moist air be permitted access during the
intervals of the using.
The magnesium formed by the foregoing process I purify by fusion in
anhydrous chloride of magnesium, which for this purpose I prefer to employ
without admixture with any other kind of flux. When the magnesium is
pulverulent it may (if previously made perfectly dry) be thrown into a small
quantity of chloride of magnesium already fused in a crucible. The crucible
cover must be instantly put on, and the heat continued for a few minutes,
more or less, according to the quantity operated upon. The cover is then
quickly removed, and the mass is compressed by a rather large and perfectly
dry and clean iron rod. As the chloride of magnesium begins to solidify (the
heat meanwhile being diminished) the metal may be compressed into
globules, which may usually be run together. The magnesium rarely takes
fire, but should this happen it is only necessary instantly to adapt the cover.
When cold, the lump magnesium may be washed with dilute acetic or nitric
acid, and then thoroughly with water. The surface of the metal is thus
brightened; but if the washing acid contain iron the latter is instantly pre-
cipitated upon the surface of the magnesium and blackens it.
I prepare anhydrous chloride of magnesium by slowly heating the hydrated
chloride to redness in a current of dry hydrochloric acid. I use; by preference,
a platinum crucible, into the cover of which two tubes are fitted, one for the
ingress and the other for the egress of the stream of hydrochloric acid gas. I
find the following to be a convenient arrangement:-A flask or other suitable
vessel containing strong sulphuric acid has an acid tube passing through its
closely fitting cork or stopper; the lower end of the tube enters the sulphuric
acid. A tube connects this flask with another vessel containing sulphuric acid
for drying the hydrochloric acid gas. This vessel is provided with a safety
tube, and with a tube which connects this vessel with the ingress tube of the
platinum crucible. The arrangement for the extrication and drying is pre-
cisely that in constant use in laboratories. All being prepared, the crucible
being charged with chloride of magnesium, previously dried at a temperature
not exceeding 130° centigrade, heat from a gas flame or otherwise is caused
to play upon the crucible, and pure hydrochloric acid is slowly poured through
the acid tube into the flask containing sulphuric acid. Hydrochloric acid gas
is rapidly extricated, and passing over the heated chloride of magnesium
contained in the crucible carries off the moisture and escapes through the
exit tube. The process of dehydrating the chloride of magnesium is soon
accomplished, the conclusion of the process being known by the crucible
attaining a full red heat when a sufficient source of heat is used. The

page_text: crucible may be allowed to cool, and the chloride of magnesium be then
dropped out, or it may be poured off on to a cold clean and dry iron plate
while the chloride is yet fluid. The hydrochloric acid gas passing out of the
crucible by the egress tube may readily be condensed by the attachment of a
tube connecting the egress tube of the crucible with a little water. After
condensation the hydrochloric acid may of course be used over again, as may
also the sulphuric acid if it be first concentrated by the evaporation of the
water which it has imbibed during the process.
Magnesium prepared by the preceding process has a silver-white color, is
very brilliant, malleable at a temperature below redness, but somewhat brittle
at common temperatures. It fuses at a red heat, and at that temperature
burns in the air, giving a brilliant white light. It is but little oxidizable at
common temperatures even in moist air, and is not sensibly affected by sul-
phuretted gases; it is acted upon by ammoniacal gases. It cannot easily be
cast in air, as it is very viscous at a temperature but just above its fusing
point, and at the temperature at which it flows readily it inevitably takes fire.
It may, however, be fused in chloride of magnesium, upon the surface of
which it floats and then be drawn up into tubes by suction, and so obtained
in ingots. It may also be fused into solid masses in iron vessels, from which
the air is excluded by coal gas, or, as is more convenient, by dry hydrogen
gas. If coal gas be employed it should be freed from sulphuretted hydrogen,
ammonia, air, and moisture. Dry hydrochloric acid gas may be passed over
fused magnesium without the latter taking fire, and the metal, if impure,
becomes purer by the process. The specific gravity of magnesium is about
1.74.
In witness whereof, I, the said Edward Sonstadt, have hereunto set
my hand and seal, this Seventh day of May, in the year of our Lord
One thousand eight hundred and sixty-three.
E. SONSTADT. (L.S.)