AN IMPROVED PROCESS FOR PREPARING HYDRATE OF MAGNESIA
Year: 1874

page_text: LETTERS PATENT to William Edward Newton, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Civil Engineer,
for the Invention of "AN IMPROVED PROCESS FOR PREPARING HYDRATE OF
MAGNESIA." A communication from abroad by Charles H. Phillips,
1
EL
PROVISIONAL SPECIFICATION left by the said William Edward
Newton at the Office of the Commissioners of Patents, with his
Petition, on the 6th January 1874.
I, WILLIAM EDWARD NEWTON, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Civil Engineer, do hereby declare
the nature of the said Invention for "AN IMPROVED PROCESS FOR PREPARING.
HYDRATE OF MAGNESIA," to be as follows:-
This Invention consists first in a process for preparing what may be.
termed a superhydrate of magnesia, by means of which it is obtained in
a pure form for medical and other purposes, and secondly, it consists in
a new preparation or compound for medical purposes, termed "milk of

page_text: magnesia" which is a mixture of the superhydrate of magnesia with pure
or distilled water.
To manufacture one hundred gallons of the milk of magnesia, one
hundred and twenty-five pounds of pure sulphate of magnesia are
taken, and dissolved in two hundred gallons of distilled water, and after-
wards filtered through paper if necessary or desirable. To this is then
added a solution of about 65 lbs. of pure caustic soda, or 90 lbs. of
potash to free and precipitate the magnesia from the sulphuric acid with
which it was previously combined.
The two solutions are thoroughly mixed with each other so as to
insure a perfect decomposition and chemical reorganization of the
elements.of the solutions used. The product of this operation is an
insoluble superhydrate of magnesia diffused through the mother liquid,
and which consists of an acqueous solution of the sulphate of the alkali
employed. The solution and mixture are allowed to settle for about
twenty-four hours, and the clear liquor then drawn off, after which more
distilled water is added and the whole thoroughly stirred and mixed,
and again allowed to settle, and the clear liquor afterwards drawn off as
before. The mixture may then be subjected to boiling for half an hour
or more through the aid of steam. While the boiling continues and
even for some little time afterwards sufficient agitation either through
the direct action of the steam or else by some suitable mechanical
appliance must be employed to prevent the coagulation and accumula-
tion on the bottom and sides of the vessel of the magnesia. This done
the solution and mixture are allowed to settle, and the clear liquor
containing a portion of the soluble sulphate of the alkali employed is
then drawn off. More distilled water is then added and the boiling is
allowed to continue, and the solution again allowed to settle and the
clear liquor is to be again drawn off. This operation may be repeated
for seven or eight times with the addition of fresh distilled water, so as
to effectually remove from the precipitated magnesia the sulphate of the
alkali formed during the process of reducing it from its state of com-
bination as a sulphate to its present condition as a superhydrate. This
done, as much pure distilled water is added as will dilute the mass of
magnesia to a thin consistency, and which shall contain about twenty
grains of pure magnesia per fluid ounce or about four times as much
'real magnesia as there is contained in any of the so-called fluid magnesia
preparations now in use.

page_text: I have described the sulphate of magnesia as the source from which I
obtain the magnesia in this preparation, but any other soluble salt of
magnesia will answer the same purpose, such as chloride of magnesium.
As a modification of the process I precipitate the magnesia from the
sulphate of magnesia with caustic alkali as before, using for this purpose
the same materials and proportions. The whole is then placed on filters
and repeatedly washed with pure distilled water until the washings no
longer give evidence of the presence of sulphates upon being tested.
The pulpy mass is then mixed through sieves and by agitation with a
sufficiency of water to bring it to the required strength in order to
produce milk of magnesia.
Instead of boiling the soluble salts of magnesia and the caustic
alkalies together, the operation may be conducted without the applica-
tion of heat in which case the same materials and proportions of materials
will be still be used, and the mixture kept in a state of agitation until the
chemical action of the caustic alkali upon the soluble salts of magnesia
employed has been thoroughly effected.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Edward Newton in the Great Seal Patent
Office on the 6th July 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of January, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Edward Newton, Her special
licence that I, the said William Edward Newton, my executors, admini-
strators, and assigns, or such others as I, the said William Edward Newton,
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,

page_text: and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "AN IMPROVED
PROCESS FOR PREPARING HYDRATE OF MAGNESIA," being a communication to
me from abroad by Charles H. Phillips, of the City and State of New
York, United States of America, upon the condition (amongst others)
that I, the said William Edward Newton, my executors, or admini-
strators, 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 William Edward Newton, 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 (that is to say) :-
:-
This Invention consists, first, in a new and improved process for pre-
paring what may be termed a superhydrate of magnesia by means of
which it is obtained in a pure form for medical and other purposes.
And, secondly, it consists in a new preparation or compound for medical
purposes, termed "milk of magnesia" which is a mixture of the super-
hydrate of magnesia as prepared by this process with pure or distilled
water in proportions to be herein-after specified. In preparing this super-
hydrate of magnesia the utmost care must be exercised as well in the
selection of the material from which it is to be made as in the con-
ducting of the process itself, in order to obtain it perfectly pure.
To manufacture one hundred gallons of the milk of magnesia one
hundred and twenty-five pounds of pure sulphate of magnesia are taken
and dissolved in two hundred gallons of distilled water, and afterwards
filtered through paper if necessary or desirable. To this is then added a
solution of pure caustic soda or potash in sufficient quantity to free and
precipitate the magnesia from the sulphuric acid with which it was
previously combined. For this purpose about fifty-seven. pounds of the
real soda, or about eighty-six pounds of the real potash completely
dissolved are requisite to produce the desired result.
The two solutions above mentioned on being added the one to the
other, are thoroughly mixed and incorporated with each other by any

page_text: suitable mechanical appliance, and although chemical decomposition
almost instantly ensues, the stirring and mixing are continued for some
time thereafter so as to ensure a perfect decomposition and chemical
reorganization of the elements of the solutions used. The length of
time necessary for such purpose need not be long, but it is advisable to
continue the agitation for from a very few minutes to half an hour, and
even a longer time may be beneficial. The product of this operation is
an insoluble superhydrate of magnesia diffused through the mother
liquid, and which consists of an aqueous solution of the sulphate of the
alkali employed. The chemical process having been completed the
solution and mixture are allowed to settle for about twenty-four hours
or thereabout, and the clear liquor then drawn off, after which more
distilled water is added in quantity sufficient to replace the liquor with-
drawn, and the whole is to be thoroughly stirred and mixed for any
suitable length of time and again allowed to settle, and the clear liquor
afterward drawn off as before.
After the second or third washings are completed and fresh water
added, say, for the fourth washing the mixture may be subjected to
boiling for half an hour or more in some suitable vessel or boiler through
the aid of steam, either by the diffusion of the steam throughout the
mass from the open end of a steam pipe or by means of steam introduced
into a double or jacketted boiler or vessel. Or it may be effected by a coil
of pipe arranged in the bottom of the vessel or boiler, through which
steam from the boiler is made to pass and be discharged either on
the
inside or outside of the boiler. Or this pipe may be perforated with a
great number of small holes, through which the steam may be injected
into the boiler in small jets for the purpose of agitating the solution, in
which event the coil if desired may be closed at its outer end, and made
removable by unscrewing the coupling which connects it with the main
steam pipe. Or instead of a coil for that purpose it may consist of a.
series of small pipes connected to one main feed pipe, and the latter
with the main steam pipe of the boiler, and from which like the others
it can be disconnected for removal if desired, or the boiling may be
accomplished in any other suitable manner. But in all cases while the
boiling continues, and even for some little time afterwards sufficient
agitation either through the direct action of the steam, or else by some
suitable mechanical appliance must be employed to prevent the coagula-
tion and accumulation on the bottom and sides of the vessel of the

page_text: magnesia. This done the solution and mixture are allowed to settle for
twenty-four hours or thereabouts as before, and the clear liquor con-
taining a portion of the soluble sulphate of the alkali employed is then
drawn off. More distilled water is then added to the boiler in quantity
sufficient to replace the liquor withdrawn, and steam or heat is applied
with agitation as before. The boiling is then allowed to continue as
long as in the former case, and the solution again allowed to settle and
which will consume about the same length of time as before, when the
clear liquor is to be again drawn off. This operation may be repeated
for seven or eight times with the addition of fresh distilled water each
time, so as to effectually remove from the precipitated magnesia the
sulphate of the alkali formed during the process of reducing it from its
state of combination as a sulphate to its present condition as a super-
hydrate.
The supernatant liquor resulting from the last boiling should not only
be tasteless, but should yield no precipitate with the exhibition to it of a
solution of nitrate of barytes (slightly acidulated with nitric acid), other-
wise the operations must be repeated until it comes up to the test
required. Or instead of using cold water for the first three or four of
the operations, the whole process may be conducted from the very :
commencement by boiling, say, for half an hour each time, but as before
agitation must be kept up during and even for some time after the
boiling process has been completed, but I prefer the former method as
the boiling of the mixture in the first place seems to impart a bitter
taste to the product, and this taste is very difficult to remove by sub- 2
sequent washings. The last or test liquor having been drawn off, the
remainder may be again washed if desired or deemed advisable with fresh
distilled water, and allowed to settle and that then drawn off also. This
done as much pure distilled water is added as will dilute the mass of
magnesia to a thin consistency and which shall contain about twenty a
grains of pure magnesia per fluid ounce, or about four times as much
real magnesia as there is contained in any of the so-called fluid magnesia
preparations now in use. This is a point of considerable importance in
administering medicine to infants and invalids, but while that is about
the strength at which it will be generally made and offered for sale, I do a
not propose to confine myself to such proportions as it may be made
weaker or stronger to any required extent in order to meet the require-
ments of the profession and the public. This is effected simply by

page_text: diminishing or increasing the quantity of water with which the
magnesia is mixed, according as the mixture is required to be made
weak or strong, but twenty grains per fluid ounce answers admirably and
may in that form be administered in suitable quantity to young or old
without hesitation or danger.
I have described the sulphate of magnesia as the source from which
the magnesia in this preparation is obtained, but any other soluble salt
of magnesia will answer the same purpose, such as chloride of magnesium.
And in regard to the caustic soda or caustic potash used, although these
articles can be obtained tolerably pure, still it is preferable to prepare
their caustic solutions from their pure carbonates by the agency of lime
and water by the usual process known to chemists, or by any other
process by which they or either of them can be obtained in a pure form.
And though silver vessels are preferred in making this preparation still
earthenware or wooden vessels may be employed..
Having thus described what is considered the best process for pro-
curing a pure superhydrate of magnesia by the action of a pure caustic.
alkali upon the soluble salts of magnesia, I may allude to a modification-
of the process which depends on filtration and washing with pure
distilled water for the separation of the alkaline sulphate from the
precipitated magnesia instead of boiling and drawing off the liquor. In.
this process the magnesia is precipitated from the sulphate of magnesia
with caustic alkali as before, using for this purpose the same materials
and proportions. The whole is then placed on filters and repeatedly
washed with pure distilled water until the washings no longer give
evidence of the presence of sulphates upon being tested with the nitrate
of barytes as before described. The pulpy mass is then mixed through
sieves and by agitation with a sufficiency of water to bring it to the
Great
required strength in order to produce milk of magnesia.
difficulties are experienced in this operation because of the insufficiency
and tediousness of the washing, and the presence of coagulated lumps of
superhydrate of magnesia, which interferes with the smoothness and
fluidity and consequent efficacy of the magnesia, for which reasons, it is
preferable to keep the magnesia in the fine state in which it is originally
precipitated by using the open steam process before described.
instead of boiling the soluble salts of magnesia and the caustic alkalies
together, the operation may be conducted without the application of
heat, in which case the same materials and proportion of materials will
Or

page_text: still be used, and the mixture kept in a state of agitation until the
chemical action of the caustic alkali upon the soluble salts of magnesia
employed has been thoroughly effected, on which the new compound is
allowed to settle and the supernatant liquor drawn off as before, and the
residuum then treated with repeated washings with pure distilled but
cold water accompanied by agitation as in the former way, it differing in
no respect from that save that the heating or boiling process is omitted,
but while a fair product can be obtained in this way, the manipulation
first described is preferred as not only being more expeditious, but for the
further reason that the product is finer and smoother, and in some 1
respects possibly purer and better.
Having thus described the Invention which has been communicated
to me by my foreign correspondent, and having explained the manner of
carrying the same into effect, what I claim as new is,―
First. The process herein described of preparing a pure superhydrate 1
of magnesia by subjecting a soluble salt of magnesia to the action of a
caustic alkali, and then treating it in the manner substantially as set
forth.
Secondly. I claim the medical compound herein described consisting
of a superhydrate of magnesia mixed with water, and termed a "milk of 2
magnesia" when prepared in the manner substantially as specified.
In witness whereof, I, the said William Edward Newton, have here-
unto set my hand and seal, the Sixth day of July, in the
year of our Lord One thousand eight hundred and seventy-four.
W F NEWTON