IMPROVEMENTS IN TREATING BONES, HORN-PITHS, PHOSPHATES, AND OTHER MATERIALS IN ORDER TO OBTAIN PRODUCTS THERE. ADDED& ATTH AD AN EMPLOYED THEREFOR "
Year: 1874

page_text: LETTERS PATENT to Andrew George Hunter, of Flint, North Wales,
for the Invention of "IMPROVEMENTS IN TREATING BONES, HORN-PITHS,
PHOSPHATES, AND OTHER MATERIALS IN ORDER TO OBTAIN PRODUCTS THERE.
ADDED&
ATTH
AD AN EMPLOYED THEREFOR
"
PROVISIONAL SPECIFICATION left by the said Andrew George Hunter
at the Office of the Commissioners of Patents, with his Petition,
on the 21st May 1874.
I, ANDREW GEORGE HUNTER, of Flint, North Wales, do hereby declare
the nature of the said Invention of "IMPROVEMENTS IN TREATING BONES,
HORN-PITHS, PHOSPHATES, AND OTHER MATERIALS IN ORDER TO OBTAIN PRODUCTS
THEREFROM, AND IN THE APPARATUS OR MEANS EMPLOYED THEREFOR," to be as
follows, that is to say :—
In the process of manufacturing glue from bones, horn-piths, and
analogous materials, as heretofore practised, by treatment with dilute
hydrochloric acid, which dissolves out their mineral constituents, it has.

page_text: been customary to precipitate the lime from such solutions by means of
sulphuric acid, thereby forming sulphate of lime, leaving hydrochloric
acid and phosphoric acid in solution. This solution may be used to treat
fresh quantities of bones, horn-piths, and analogous materials, which will
have the effect of accumulating phosphoric acid in the solution.
It has been customary to allow the accumulating phosphoric acid to
pass off from the process by leaving it adhering to the precipitated
sulphate of lime, and disposing of that for land fertilizing purposes, but
this has the disadvantage of being contaminated by the adhering hydro-
chloric acid, thereby reducing its commercial and fertilizing value,
besides involving the waste of such adhering hydrochloric acid.
Part of the improvements constituting this Invention relate to a mode
of avoiding such loss of hydrochloric acid, and at the same time securing
the phosphoric acid in a state available for the manufacture of phosphorus.
This is effected by thoroughly washing with water the afore-mentioned
precipitated sulphate of lime, thereby removing in such washings the
adhering hydrochloric and phosphoric acids. These washings are added
to the principal solution of hydrochloric and phosphoric acids, from
which the said sulphate of lime has been previously precipitated, and the
whole solution is then placed in evaporating pans provided with covers,
and with connections to convey the vapours to condensing apparatus, in
which the hydrochloric acid as evaporated by heat may be condensed and
conveyed to receiving tanks for future use.
Copper pans arched over and heated by flame passing over the surface
of the solution and below the arch are found suitable, the evaporated
acid vapours and the flame passing off together to the condensing
apparatus.
Coke filled towers similar to those used by alkali makers for condensing
hydrochloric acid are suitable for the purposes of this Invention. The
result of such evaporation is that the hydrochloric acid is volatilized,
conveyed to the condensers, and thereby obtained for further use, leaving
phosphoric acid in the pan in a concentrated state..
In the manufacture of phosphorus as hitherto practised it has been
customary to place the phosphoric acid in the distilling retorts partially
combined with lime, usually as monobasic or bibasic phosphate of lime,
or as a mixture of both, and in the distilling operation (which has been
conducted in comparatively small retorts by intermittent distillation, i.e.,

page_text: the retort being filled and emptied separately for every charge) sufficient
of the phosphoric acid is deoxidized and volatilized partially as phos-
phorus and partially as phosphoretted hydrogen (which if oxidized may
be condensed and recovered for further use as phosphoric acid) to reduce
the quantity left in the retort to merely enough to combine with the
lime present to form tribasic phosphate of lime. The effect of this is
that a large proportion of the phosphoric acid originally placed in the
retort remains in it unvolatilized. It has been attempted to avoid this
loss by placing the phosphoric acid in the retort in a free state, i.e., un-
combined with lime, but it was found that the phosphoric acid distilled
over as such, it being volatile at a lower temperature than that requisito
for its deoxidation by carbon.
The improvements forming part of this Invention avoid the leaving of
phosphoric acid in the retort or allowing it to distill over unchanged.
This is effected by taking the phosphoric acid freed from lime by preci-
pitation by sulphuric acid, and from which the hydrochoric acid has
been removed by evaporation, as herein-before described, mixing it with
the requisite quantity of carbon (which is most advantageously employed
in excess of the quantity requisite for combining with all the oxygen
present, that quantity being readily determined by the chemical equiva-
lents, as well understood by chemists), evaporating the whole to complete
dryness and placing the dry mass in improved retorts which are con-
structed and operated as herein-aftor described, and which effect the
following improvements:-
First. Continuous distillation, thereby effecting a large saving in fuel
and breakage of retorts over the usual intermittent mode.
Second. That the volatilized phosphoric acid shall previously to
being permitted to pass to the condensing apparatus be brought into
intimate contact with carbon at a temperature sufficiently. high to
deoxidize it. This latter result may be attained either by the continuous
distillation process and retorts, or if the distillation is intermittent by
placing in such retorts (and the distillation is intended to be completed in
one such retort) a quantity of carbon, and raising it to a white heat before
charging the retort with the phosphoric acid mixture, or by the employ-
ment of two or more retorts, one or more containing carbon, maintained
at a white beat, the other or others containing the phosphoric acid
mixture, the volatilized products from the said acid being passed by
means of suitable connecting pipes, which may be provided with self-

page_text: acting or other valves through one or more carbon filled retorts before
passing to the condensers. Such retorts may be set horizontally, vertically,
or at any angle. For continuous distillation retorts they may advan-
tageously be set vertically, and provided with properly arranged valves
above and below, by means of which they may be charged and emptied
while at work without permitting access of air to their interior.
By charging these retorts above and withdrawing from below the
charge continuously passes downwards, and arrives at the bottom in a
spent condition. The exit pipe or connection from the retort to the
condensers, and which may be provided with self-acting or other valves,
and with self-acting or other openings for the admission of air when
required, is most advantageously placed near the bottom of the retort
above the discharging valves, thereby forcing all the volatilized products
to traverse nearly the entire length of the retorts, and especially that
portion which is maintained at the highest degree of heat, so that phos-
phoric acid volatilized as such in the upper portion of the retort shall in
its descent to the exit pipe pass through a mass of carbon (being the
excess carbon of previous charges) maintained at a white heat, and
thereby become deoxidized before passing to the condensers.
In continuous as well as in intermittent distillation one or more retorts
may be used, one or more containing the phosphorized acid mixture, and
one or more containing carbon, maintained at a white heat, the vola-
tilized products from the phosphoric acid retorts being caused by means
of connecting pipes provided with self-acting or other valves to traverse
one or more carbon filled retorts before passing to the condensers, or the
entire process may be conducted in one retort, as already described.
It will be understood that the improved method of distilling phosphoric
acid for conversion into phosphorus is applicable to phosphoric acid
whether derived as herein-before described, or by extraction from bones,
horn-piths, bone ash, or phosphates of lime, by means of sulphuric or
other acid, directly or indirectly, and is also applicable to the distillation
of monobasic or bibasic phosphates of lime, with or without the addition
to the phosphate mixture of silicic acid and to the distillation of tribasic
phosphate of lime when mixed with silicic acid, such silicic acid being
employed either in the state of sand, quartz, &c., finely ground, or as
precipitated or gelatinous silica.
Part of the improvements constituting this Invention relate to the
employment of gelatinous or precipitated silica as a means of decomposing

page_text: phosphates of lime and of soda or potash, which may be mixed with the
gelatinous silica and carbon throughly dried and then distilled, as hercin-
before described. Precipitated tribasic phosphate of lime is a convenient
form to use for mixing with the gelatinous silica, as thereby a very
intimate mixture of their respective particles may be obtained. Such
gelatinous silica may be obtained by any of the means well known to
chemists, or by precipitation from a solution of silicate of soda or potash
by means of phosphoric acid, thereby obtaining gelatinous silica and
phosphate of soda or potash, which may be utilized as such, or decom-
posed by being intimately mixed with silica and carbon, thoroughly
dried and distilled, thereby obtaining the phosphorus as such, and re-
forming silicate of soda or potash, which when dissolved with or without
(as may be needed) additional alkali is available for the further pro-
duction of gelatinous silica.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Andrew George Hunter in the Great Seal Patent
Office on the 19th November 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
GEORGE HUNTER, of Flint, North Wales, 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 seventy-four, in the
37th year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Andrew George Hunter, Her special
license that I, the said Andrew George Hunter, my executors, admi-
nistrators, and assigns, or such others as I, the said Andrew George
Hunter, my executors, administrators, or 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, usc, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN TREATING BONES, HORN-PITHS, PHOSPHATES, AND OTHER
MATERIALS IN ORDER TO OBTAIN PRODUCTS THEREFROM, AND IN THE APPARATUS OR
MEANS EMPLOYED THEREFOR," upon the condition (amongst others) that I,

page_text: the said Andrew George Hunter, by an instrument in writing under
my hand and seal, 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 Andrew George Hunter, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the accompanying
Drawings and to the letters and figures marked thereon, that is to
say :-
In the process of manufacturing glue from bones, horn-piths, and
analogous materials as heretofore practised (by treatment with dilute
hydrochloric acid, which dissolves out their mineral constituents) it has
been customary to precipitate the lime from such solution by means of
sulphuric acid, thereby forming sulphate of lime, leaving hydrochloric
and phosphoric acids in solution. This solution is again used to treat
fresh quantities of bones, horn-piths, and analogous materials, which has
the effect of accumulating phosphoric acid in the solution.
The accumulating phosphoric acid has hitherto been allowed to pass
off from the process by leaving it adhering to the precipitated sulphate
of lime, and disposing of such precipitate for land fertilizing purposes,
.but this has the disadvantage of being contaminated by the adhering
hydrochloric acid, whereby the commercial and fertilizing value of a
the said precipitated sulphate of lime and adhering phosphoric acid
is reduced, besides involving the waste of the adhering hydrochloric
acid.
Part of the improvements constituting my said Invention relates to a
mode of avoiding such loss of hydrochloric acid, and at the same time
securing the phosphoric acid in a state available for the manufacture of
phosphorus. This is effected by adding sulphuric acid in sufficient
quantity, and no more, to combine exactly with all the limo present in
the hydrochloric acid solution obtained from the bones, horn-piths, and
other analogous materials, and allowing the insoluble sulphate of lime g
to settle. The supernatent liquor containing the hydrochloric acid and
phosphoric acid in solution is then decanted or drawn off, and the

page_text: precipitated sulphate of lime thoroughly washed with water. The
washings from the sulphate of limo are added to the principal solution
of hydrochloric acid and phosphoric acid, which has been substantially
freed from lime by the sulphuric acid, as herein-before described, and
the whole solution is then placed in evaporating pans or furnaces
provided with covers, and with connexions to convey the vapours to
condensing apparatus, in which the hydrochloric acid as evaporated by
heat is condensed and conveyed to receiving tanks for future use.
As the evaporation of the hydrochloric acid proceeds such portions of
sulphate of lime as have not been precipitated from the liquid will
gradually separate from the solution in the pans, which sulphate of lime
is removed from time to time and washed with water, the washings
being added to the principal solution of hydrochloric and phosphoric
acids as before.
The evaporation and concentration of the hydrochloric and phosphoric
acid solution is conducted in pans composed of copper, iron, pitch pine,
or other suitable substance, which pans may be lined with or may be
entirely constructed of bricks, stone, or other refractory material in order
to prevent the acid solution, heat, and fumes or vapour from coming in
contact with and damaging tho metal or wooden pan. The pans are
arched over and heated by flame passing either under and around them,
or under the arch and over the surface of the solution, the evaporated acid
vapours when heated and the products of combustion thereafter passing
off to the condensing apparatus. The result of such evaporation is that
the hydrochloric acid is volatilized, and being conveyed to the condensers'
and condensed is thereby obtained for further use, leaving phosphoric
acid in the pan in a concentrated state.
Coke filled towers similar to those used by alkali makers for con-.
densing hydrochloric acid are suitable for employment as condensers for.
the purposes of this Invention, but it is to be understood that I do not,
confine myself to any particular arrangement of hydrochloric acid
condensers, nor to the arrangement of evaporating pan herein-before
referred to, as any other suitable arrangement of such pans or condensers
may be adopted.
In the manufacture of phosphorus, as hitherto practised, it has been.
customary to place the phosphoric acid in the distilling retorts, partially
combined with lime, usually as mono-basic or bi-basic phosphate of lime,

page_text: or as a mixture of both, and in the distilling operation (which has been
conducted in comparatively small retorts by intermittent distillation,
that is, the retort being filled and emptied separately for every charge)
sufficient of the phosphoric acid is deoxidized and volatilized, partially
as phosphorus, and partially as phosphorated hydrogen (which if
oxidized may be condensed and recovered for further use as phosphoric
acid) to reduce the quantity left in the retort to merely enough to
combine with the lime present to form tri-basic phosphate of lime,
which does not evolve phosphorus by the sole action of heated carbon.
The effect of this is that a large proportion of the phosphoric acid
originally placed in the retort remains in it unvolatilized, and it has
been attempted to overcome or avoid this loss by placing the phosphoric
acid in the retort in a free state, that is to say, uncombined with lime,
but it is found under this mode of working that the phosphoric acid
distills over as such, the acid being volatile at a lower temperature than
that requisite for its deoxidation by carbon.
Another part of my said Invention consists in improvements in the
manufacture of phosphorus, whereby the leaving of phosphoric acid in
the retorts, or allowing it to distill over unchanged is avoided. This is
effected by taking phosphoric acid freed from lime by precipitation with
sulphuric acid, and from which the hydrochloric acid and sulphate of
lime have been removed by evaporation, as herein-before described,
mixing it with the requisite quantity of carbon (which is most advan-
tageously employed in excess of the quantity required for combination
with all the oxygen present in the phosphoric acid, that quantity being
readily determined by the chemical equivalents involved, as is well
understood by chemists), evaporating the whole to complete dryness,
and placing the dry mass, herein-after called the phosphoric acid
mixture, in improved arrangements of retorts, constructed and operated
as herein-after described, and by which the following results are
obtained :-
First. Continuous distillation, thereby effecting a large saving in fuel
and breakage of retorts over the usual intermittent mode of working.
Second. That the volatilized phosphoric acid, previously to being per-
mitted to pass to the condensing apparatus, is brought into intimate
contact with carbon at a temperature sufficiently high to deoxidize and
reduce it to phosphous. This latter result may be attained either by
the continuous distillation process and retorts, as herein-after described,

page_text: or, if the distillation is intermittent (and if it is intended that the dis-
tillation be completed in one retort); by placing in such retorts a quantity
of carbon in addition to that mixed with the phosphoric acid, and raising
it to a white heat before materially heating that portion of the retort
containing the phosphoric acid mixture, or before the said mixture
into the retort. The volatilized products from the phosphoric acid
mixture are caused to traverse intimately through or amongst the
white hot carbon before reaching the outlet to the condensing apparatus.
The same result may be attained by the employment of two or more
retorts, one or more containing carbon maintained at a white heat, the
other or others containing the phosphoric acid mixture, the volatilized
products from which are passed by means of suitable pipes, which are or
may be provided with self-acting or other valves, through one or more
carbon filled retorts, the contents of which are maintained at a white
heat, and deoxidized and converted into phosphorus before passing off to
the condensers. The retorts employed under this Invention may be set
horizontally, vertically, or at any desired angle, and modified in con-
struction and in the manner of operation to suit the different retorts and
setting of the same. For continuous distillation the retorts may advan-
tageously be set vertically, and be provided with one or more valves in
addition to the doors at their upper and lower ends, by means of which
they may be charged and emptied whilst in operation, and without per-
mitting access of air to their interiors, but for intermittent distillation
such valves may be dispensed with.
By charging the retorts from above, and withdrawing their solid
contents from below, the phosphoric acid mixture continuously passes
downwards, and arrives at the bottom in a spent condition. For phos-
phorus distillation retorts the exit pipe or connexion between the retort
and the condensers may be provided with self acting or other valves for
the passage of the volatilzed products, and with self acting or other
openings for the admission of air thereinto when required, and in retorts
set in a vertical position the said pipe may be advantageously placed
near the bottom of the retort, and above the valve for discharging the
spent material, by which means all the volatilized products of each suc-
cessive charge of phosphoric acid mixture are caused to traverse nearly
the entire or throughout a great portion of the length of the retort, and
especially that portion which is most highly heated, and wherein the
excess or unused carbon of former charges is maintained at a white heat,

page_text: by which means the phosphoric acid, volatilized as such in the upper
part of the retort, is deoxidized or converted into phosphorus before
passing off from the retort to the condensers.
And in order that the construction and operation of the retorts
employed in continuous as well as in intermittent distillation of phos-
phoric acid in the manufacture of phosphorus according to my said
Invention may be properly understood, I have hereunto appended a
Sheet of explanatory Drawings on which Figure 1 is a section of one
form or construction of vertical retort which may be used in the said
manufacture. The retort A (which may be entirely of fire-clay, or of
iron lined with fire-clay, or partly of fire-clay and partly of iron or other
suitable material) is charged through a hopper B or through a doorway
situate at its upper end, from whence the phosphoric acid mixture falls
on to the sliding valve or door C, which fits the interior of the retort.
When a quantity of the phosphoric acid mixture sufficient for one
charge has been deposited on the door C the hopper or doorway at B is
closed and the sliding valve or door C is withdrawn, whereby the mixture
is allowed to fall on to the valve or cone D, which is operated vertically
within the retort by the screw a or its mechanical equivalent. After the
door or valve C has been returned to its place so as to shut off communi-
cation between the portions of the retort above and below the said door,
and thereby prevent the passage of air downwards through the retort,
another charge of phosphoric acid mixture is deposited upon it; the
drop valve or cone D is then lowered, and the phosphoric acid mixture
is thereby deposited on the valve E, which, when the valve D has been
returned to the position shewn on Figure 1 and another charge of
phosphoric acid mixture dropped on to it and another on to C, is turned
or tilted up by the hand wheel b, or other suitable means, and by this
arrangement the phosphoric acid mixture is deposited within the working
space of the retort. In intermittent distillation these valves may be
dispensed with, the retort being charged directly through the door at
top and the spent charge withdrawn directly through the door at the
bottom.
By the action of heat applied to the outside of the retort A the
phosphoric acid contained in the said charge of phosphoric acid mixture
is volatilized partially as phosphorus and partially as phosphoric acid in
the upper part of the retort, from whence the vapours pass downwards
through the white hot carbon above the sliding door or valve F, whereby

page_text: the phosphoric acid vapours are deoxidized, and thereafter all the vapours
pass off through the pipe G to the condensers, which pipe is provided
with a self-acting or other air valve c to admit of the passage of air
thereinto when necessary, and with a self-regulating ball or other form
of valve at d to admit of the passage of the vapours and to prent air
from passing into the retort at that point. The white hot carbon at the
lower end of the retort is (when the conversion process has been some
time in operation) the excess or unused carbon of the phosphoric acid
mixture from which the phosphoric acid vapours have been volatilized
previous to reaching the lower end of the retort, it being understood
that in continuous distillation so soon as the emission of vapour from
each successive charge ceases or becomes diminished a fresh quantity of
the phosphoric acid mixture is charged into the retort, as herein-beforo
described, thus pressing the carbon or residue of the previous charge
nearer to the lower or more highly heated portion of the retort, and
whereat it is raised to a white heat. In starting the operation of
vaporizing the phosphoric acid mixture a quantity of carbon unmixed
with phosphoric acid, and sufficient to fill the retort to from % to % of
its working space, is placed therein and raised to a white heat before
charging the phosphoric acid mixture above it.
When practising continuous distillation a quantity of the spent
carbon or spent phosphoric acid mixture is removed from the bottom of
the rotort at each successive fresh charge of phosphoric acid mixture
above, or at such other times when removal is necessary, by withdrawing
the valve or door F, whereby the contents of the retort are allowed to
drop on to the valve H%; the door or valve F is then returned to the
position shewn on the Drawings, and the valve H is turned or canted so
as to deposit the amount of spent charge contained between it and the
valve Fon to the drop valve or cone I, which is operated by the
screw d, and wedge e, or other mechanical equivalent, and by lowering
which, after the valve H has been returned to its position for closing
communication with the upper part of the retort, the said quantity of
spent carbonaceous matter is deposited at the lower end of the retort,
from whence it is removed through the doorway J after the valve I has
been returned to its raised position. The carbon withdrawn from the
retorts may, if not too highly charged with mineral substances, be used
for admixture with fresh quantities of phosphoric acid, or may be
cleansed from such mineral substances and then used.

page_text: When employing a single retort similar to that herein-before
described in intermittent distillation, the vapour exit pipe may be placed
either at the top or bottom of the retort; if at the top phosphoric acid
mixture is first charged into the retort in quantity sufficient to fill it
from 1 to 1 of its length, and sufficient carbon to fill the remaining
working space of the retort is charged on the top of the said mixture,
and raised to a white heat before the lower part of the retort is
materially heated. If the vapour exit pipe is at the lower end of the
retort, then carbon is first charged thereinto in quantity and heated,
as herein-before described.
Valves differing in shape, construction, and operation from those
illustrated may be used; or valves, such as are illustrated at Figure 1,
may be differently placed without departing from the principle of my
Invention.
Figure 2, on the appended Sheet of Drawings, is a longitudinal section
of a horizontal retort (which may be constructed of fire-clay or of iron
lined with fire-clay or of other suitable material) adapted to convert
phosphoric acid into phosphorus, in accordance with my said Invention
by the intermittent process. A is the space of the retort into which
carbon is first placed in quantity sufficient to fill from %, to % of the retort,
and wherein the carbon is raised to a white heat before the phosphoric
acid mixture charged into the retort through the doorway B is materially
heated. The vapor exit pipe C, which is provided with a self-acting
valve 6 for passage of the vapor, and a valve a for admission of air
to the pipe when necessary, is most advantageously placed in the rear
of the retort, and as low as possible, its communication with the retort
being covered with a grating or perforated plate D, as shewn, to prevent
carbon from entering into the pipe. A perforated plate or grating E is
also provided, by which the carbon occupying the rear of the retort is
from time to time or continuously forced back, and so compelled to fill
the entire vertical area of the retort, thus overcoming the tendency of
the carbon to settle, and leave a vacant space or channel above it,
through which the volatilized products from the said mixture might, if
not thus prevented, pass without being brought into sufficiently intimate
contact with the white hot carbon. The perforated plate or grating E
is attached to a screw F, which works through the door G and cross
bar H, by which the door is retained in position. On the outer end of
the screw F a drum I is placed, on which one end of a rope or chain is

page_text: wound, the said rope or chain being carried round pulleys J and K,
and weighted at its outer end, as shewn at L; or the weight may be
attached to the lower pulley, by which means the screw F is turned
round continuously, and thereby presses the perforated plate or grating E
against the carbon.
Previous to commencing the operation the rope or chain is wound up
on the drum I, and the grating drawn out by turning the screw F with
the handle M. In lieu of this arrangement for pressing back the carbon
the grating E may be attached to levers or other equivalent mechanism,
which or the above described process may be worked by weights, springs,
steam, compressed air, or water, or the carbon may be pressed back by
hand.
It is to be here understood that I do not confine myself to the arrange-
ment of vertical and horizontal retorts and apparatus in connexion
therewith, herein-before described, as such retorts may be considerably
modified without departure from my said Invention; and it is also to be
understood that the processes herein-before set forth of distilling phos-
phoric acid for conversion into phosphorus are applicable to phosphoric
acid, whether derived, as herein-before described, by extraction from
bones, horn-piths, bone ash, or other analogous materials, or from phos-
phates of lime, soda, potash, iron, alumina, or magnesia, by means of
sulphuric or other acid directly or indirectly; also that the process is
applicable to the distillation of monobasic or bibasic phosphates with
or without the addition to the phosphate mixture of silicic acid and to
the distillation of tribasic phosphates when mixed with silicic acid, such
silicic acid being employed either in the state of sand, quartz, or other
similar form, and finely ground; or precipitated or gelatinous silica may
be used, as now about to be described.
Part of the improvements constituting my said Invention relates to
the employment of gelatinous or precipitated silica as a means of de-
composing phosphates of lime, alumina, magnesia, iron, soda, or potash,
which may be mixed with the gelatinous silica and with carbon,
thoroughly dried, and then distilled, as herein-before described. When
treating phosphates of lime, magnesia, soda, or potash, in order to obtain
the greatest yield of phosphorus therefrom the quantity of silica
employed should be at least sufficient to form bisilicates with the bases
present, and when treating phosphates of alumina or of iron it is

page_text: advisable to employ sufficient silica to form sesquisilicates with those
bases, the respective quantities necessary in each case being readily
determined by their chemical equivalents, as is well understood by
chemists. Precipitated tribasic phosphate of lime is a convenient form
to use for mixing with the gelatinous silica, as thereby a very intimate
admixture of their respective particles may be obtained, such gelatinous
silica may be obtained by any of the means well known or usually
employed by chemists, or by precipitation from a solution of silicate of
soda or potash by means of phosphoric acid, thereby obtaining gelatinous
silica and phosphate of soda or potash which may be utilized as such or
decomposed by being intimately mixed with silica and an excess of
carbon and thoroughly dried and distilled in the phosphorus retorts,
thereby obtaining the phosphorus as such, and reforming silicate of
soda or potash, which when dissolved with or without (as may be
required) additional alkali is available for the further production of
gelatinous silica.
.
Having now described and particularly ascertained the nature of my
said Invention, and the system, mode, or manner in or under which the
same is, or may be used, or carried into effect, I would observe in con-
clusion that what I consider to be novel and original and therefore claim
as the Invention secured to me by the herein-before in part recited
Letters Patent is,-
First. The process and arrangement of apparatus whereby the con-
stituents of bones, horn-piths, and other analogous substances are
obtained, as glue or gelatine fertilizers, sulphate of lime and phosphorus,
and the bydrochloric acid recovered for further use, substantially as
herein-before described.
Second. The retorts set vertically or at a suitable angle and con-
structed and operated substantially as herein-before described in reference
to Figure 1 of the Drawings, and the employment of the said retorts in
-the continuous or intermittent distillation of phosphorus.
Third. The arrangements of mechanism whereby the carbon is pressed
back in horizontal or inclined retorts for the distillation of phosphorus,
substantially as herein-before described in reference to Figure 2 of the
Drawings.
Fourth. Placing the exit pipe in horizontal or inclined phosphorus
distilling retorts at the lower side of the retort, providing it with an

page_text: inlet valve to prevent the formation of a vacuum and a self-acting valve
to prevent back flow into the retort and covering the entrance to the
said pipe from the retort with a grating, whereby solid matter is pre-
vented from entering thercinto, substantially as herein-before described
in reference to Figure 2 of the Drawings.
Fifth. Decomposing phosphates by means of gelatinous or precipitated
silica, substantially as herein-before described.
Sixth. Producing gelatinous silica and phosphates of soda and potash
from silicates of soda and potash by precipitation with phosphoric acid,
substantially as herein-before described.
Seventh. Obtaining phosphorus from phosphates of soda or potash
admixed with silica by distillation, and recovering the silicate of soda or
silicate of potash for the production of gelatinous silica, substantially as
herein-before set forth.
Eighth. Obtaining phosphorus from precipitated tribasic phosphate
of lime by distillation with silica, substantially as herein-before described.
Ninth. The process of producing phosphorus from phosphates of
lime, magnesia, alumina, iron, soda, and potash, and for the subsequent
recovery of the said soda and potash, substantially as herein-before
described.
In witness whereof, I, the said Andrew George Hunter, have here-
unto set my hand and seal, this Ninth day of November, One
thousand eight hundred and seventy-four.
ANDREW GEORGE HUNTER. (L.S.)