Manufacture or Production of certain Substances from Birch Bark.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Manufacture or Production of certain Substances from Birch Bark.
I, JAMES WHEELER, of 100, High Street, Ilfracombe, in the County of Devon,
l'harmaceutical Chemist, do hereby declare the nature of this invention to be as
follows:
"
According to this invention I produce pyrobetulin or "pyrobatulin
anhydride" by burning in a closed chamber, without flame, and in a current of
air, material containing betulin to an amount bearing a suitable ratio to the
capacity of the said chamber. In order to obtain pyrobetulin the material is
burnt with an abundant air-supply, whereas to obtain pyrobetulin anhydride
the material is burnt with a restricted air-supply, with the result that in the former
case there is burnt away the cortical investment of the betulin of the bark and in
the latter case the pyrobetulin, thus produced is converted into its anhydride by
the more prolonged heating, and slower evolution of the fumes.
In carrying my invention into
practical effect I may employ the combustible
material in the form of tablets or small blocks (hereinafter called tablets) made
by compressing together a mixture comprising finely ground epidermis of birch-
bark preferably that of white birch or Betula alba-and an oxygen-carrier such as
nitrate of potassium. The percentage of nitrate of potassium. in the material may
vary for the production of pyrobetulin the percentage may vary from to 8, and
for producing pyrobetulin anhydride it may vary from 1 to 4; when less than
2 per cent. of nitrate of potassium is used the material should be dried for a
considerable time both before and after compression. In the case of
high percentages of nitrate of potassium it is advisable to dissolve the
nitrate of potassium either in plain water or in a weak solution
of dextrin, so as, for example, to give 1 per cent. of dextrin to the amount of bark
used. In order to produce pyrobetulin, the tablets are arranged so as to give a
space around each to allow of the free passage of an ample supply of air, whereas
to produce pyrobetulin anhydride the tablets are placed near together so as
to insure a restricted passage of air, whereby a slower combustion will be attained
than with the former arrangement.
A suitable apparatus for the manufacture or production of pyrobetulin and
pyrobetulin anhydride according to this invention comprises a chamber of sheet-
zine which has in its top an opening, preferably of circular shape, through which
it communicates with an upper compartment formed by a conical cover that fits
upon the top of the said chamber, forming therewith around the said opening an
air-tight joint by means of an india-rubber ring and a flange or other suitable
The bottom of the chamber may be closed in a sufficiently air-tight
manner by placing it upon a thick cloth or other compressible material. At
the centre of the opening there is supported from the top of the chamber, by means
of bars soldered or otherwise secured thereto, a suitable stand for a lamp in which
to burn the tablets. This lamp may comprise a cylindrical cup perforated at its
lower part to admit air and adapted in its upper part to support, by means of
brackets, a floor-plate on which is placed a ring or distance-piece, which supports
means.

page_text: a charge plate in which the tablets are arranged with their lower edges resting
biore or less on the noor-piate. 10 produce pyrobetulin, the tioor-plate may
advantageously consist of two concentric rings or metal connected by radial pieces
of metal,and ine charge plate may be a plate of metal having a number of radial
openings made through it for the due retention of the tablets with an air-space
around each, other openings, some radial and between adjacent ones of the
aforesaid radial openings and some near the centre of the plate being made through
the plate, for the passage of air therethrough; the edges of the tablets will then
rest more or less on the inner ring. For a larger lamp the floor-plate may have
two or more concentric inner rings and the charge-piate a corresponding number
of concentric rings of tablet-containing holes (of any desired capacity according
to the size of the tablets employed) with intervening air-holes. For producing
pyrobetulin anhydride the floor-plate may advantageously consist of a metal ring
having opposite sides connected together by a number of parallel bars and the
charge-plate may consist of a similar ring having two intersecting sets of bars
that connect opposite sides but are placed at a comparatively great distance apart
and between which the tablets are arranged near together transversely to the bars
of the floor-plate. The tablet-containing holes or spaces of the charge-plates,
whether for producing pyrobetulin or for producing pyrobetulin anhydride may
be made with sinuous outlines or otherwise so as to prevent the checking of the
extrication of the fumes that might otherwise occur through the swelling of the
tablets, especially in the case of large tablets. The lamp is provided with a
chimney of wire gauze, which rests on and within a collar secured to the
aforesaid cup. Besides acting as a support to the chimney, the collar just
mentioned serves to prevent air from entering the chimney between the latter
and the cup to any injurious degree.
In using apparatus constructed as described, the tablets, having been suitably
arranged in the lamp as hereinbefore described, are ignited simultaneously by
means of a jet or jets of gas caused to play upon their upper surfaces, and, any
flame produced having been extinguished, the chimney of the lamp is placed
upon its cup and the lamp put upon its stand. The conical cover is then placed in
position, whereupon the fumes, on being formed, rise upwards to the top of the
conical cover which deflects them downwards and causes them to descend into the
chamber. It is advisable that, especially in cold weather, the lamp and its charge
should when arranged for producing pyrobetulin anhydride be preparatorily heated
as much as consistent with its proper handling, in order more completely to
prevent at the outset the evolution of low-temperature fumes adapted to produce
pyrobetulin.
Apertures, normally closed by screw plugs, are provided at opposite ends of
the chamber and after a charge has been burnt, and before igniting a new one,
the cover is removed and fresh air is pumped or blown through these apertures
to displace the air that is no longer capable of supporting combustion.
I have obtained satisfactory results with an apparatus as above described in which
the chamber had a length of 22 inches, a breadth of 16 inches, and a depth of
8 inches, whilst the opening in its top was 9 inches in diameter, the height
of the cover 12 inches, and the diameter of the cup of the lamp 24 inches, this
being adapted for small circular tablets of about ½ inch in diameter. With this
apparatus I have employed tablets to the full extent of the respective charge-
plates. The cover here described would be large enough for a chamber very
considerably larger than the one here referred to.
In the case of a chamber of very large area a hook or ring attached to each
corner and connected with a common rope or chain passing over an overhead
pulley is convenient for raising the chamber to allow of the removal of the deposited
material from the floor of the chamber. Furthermore, the conical cover may be
made in two parts forming an air-tight joint with each other by means of
flanges, the lower part supporting the stand for the lamp, and having one or
more internal annular grooved depressions or channels adapted to prevent

page_text: condensed moisture from running down and falling upon the deposited pyrobetulin
or pyrobetulin anhydride.
For reducing the epidermis of birch-bark to a sufficiently fine powder to produce
the combustible material or tablets, I first pass it through a disintegrator until it
is reduced to a finely shredded condition; I then dry it by exposing it to the air
freely and to a temperature of 150° F. during three days; and 1 then pass it
repeatedly under heavy stone edge-runners unul sufficiently fine to pass through
a sieve having sixty holes to the linear inch.
When material containing betulin is burnt under the conditions hereinbefore
described, the cortical investment (in the case of birch-bark) or other matter
surrounding or enclosing the betulin becomes by contact with the burning zone
heated to such an extent that, aided by the current of air produced by the heat of
combustion, it volatilizes the betulin.
When the tablets are arranged near together so as to give a limited air-supply
the temperature of combustion and relatively long heating are such as to eliminate
more or less completely a molecule of water and thus to produce pyrobetulin
anhydride, but when the tablets are so arranged as each to have an abundant air-
supply the temperature of combustion is too low and the evolution of the fumes
too rapid to effect this elimination, with the result that pyrobetulin itself is
deposited in the chamber.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.
Manufacture or Production of certain stances from DcH DIA.
I, JAMES WHEELER, of 100, High Street, Ilfracombe, in the County of Devon.
Pharmaceutical Chemist, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
According to this invention I produce certain substances which I term "pyro-
betulin" and "pyro-betulin anhydride," by burning in a closed chamber, without
flame, and in a current of air, material containing betulin to an amount bearing
a suitable ratio to the capacity of the said chamber. In order to produce pyro-
betulin, the material is burnt with an abundant air-supply, whereas to obtain
pyro-betulin anhydride the material is burnt with a restricted air-supply.
In carrying my invention into practical effect I employ the combustible material
in the form of tablets or small blocks (hereinafter called tablets) made by com-
pressing together a mixture comprising finely ground epidermis of birch-bark-
preferably that of white birch (Betula alba)-and an oxygen-carrier such as nitrate
of potassium. The percentage of nitrate of potassium in the material may vary:
for the production of pyro-betulin the percentage may vary from 4 to 8, and for
producing pyro-betulin anhydride it may vary from about 1 to 4; when less than
2 per cent. of nitrate of potassium is used, the material should be dried for a
considerable time both before and after compression. In order to prevent flame
from arising through the deflagration of the particles of nitrate of potassium
(especially in the case of high percentages of nitrate of potassium), it is advisable
to dissolve the nitrate of potassium, before admixture with the bark, either in
plain water or in a weak solution of dextrin, so as, for example, to give one per cent.

page_text: of dextrin to the amount of bark used. In order to produce pyro-betulin,
the tablets are arranged so as to give an air-space around each to allow of the free
passage of an ample supply of air and an unobstructed evolution of the fumes,
whereas to produce pyro-betulin anhydride the tablets are placed near together so
as to insure a restricted passage of air, whereby a slower combustion and a
correspondingly slower extrication of the fumes will be attained than with the
former arrangement.
To
A suitable apparatus for the manufacture or production of pyro-betulin and pyro-
betulin anhydride according to this invention comprises, as illustrated by Figs. 1
and 2 of the accompanying drawings (which are sectional views taken of an
example at right angles to each other), a chamber 1 of sheet zinc which has in its
top an opening 2, which is preferably circular and through which it communicates
with an upper compartment 3 formed by a conical cover 4 that fits upon the top
of the chamber 1, forming therewith around the opening 2 and air-tight joint,
as by means of an india rubber ring 5 and a flange 6. The bottom of the chamber 1
may be closed in a sufficiently air-tight manner by placing it upon suitable com-
pressible material such as a thick cloth; or the bottom edge of the chamber 1 may
be provided with a suitable metal flange, or be covered with india rubber, so as to
make an air-tight joint with the floor of the chamber, which should be of suitable
non-absorbent material such as slate. At the centre of the opening 2 there is
supported from the top of the chamber, by means of bars 7 (see Fig. 3) secured, as
by soldering, thereto, a suitable stand 8 for a lamp in which to burn the tablets.
This lamp may, as shown half in vertical section and half in elevation in Fig. 4,
comprise a cylindrical cup 9 provided with circular or other perforations 9" at its
lower part to admit air, and preferably furnished with a movable ring 9b having
perforations 9 corresponding to the perforations 9" to enable the ingress of air to
be regulated at will; the cup 9 is adapted in its upper part to support, by means
of brackets 10, a floor-plate 11 on which is placed a ring or distance-piece 12
(shown in elevation in Fig 6) which supports a charge-plate 13 in which the tablets
are arranged with their lower edges resting more or less on the floor-plate 11.
produce pyro-betulin, the floor-plate may advantageously consist, as shown in plan
in Fig. 7, of two concentric rings 14 and 15 of metal connected by radial pieces 16
of metal, and the charge-plate 13 may, as shown in plan in Fig. 5, be a plate of
metal having a number of radial openings 17 made through it for the due retention
of the tablets with an air-space around each. other openings 17, some radial and
between adjacent radial openings 17 and some near the centre of the plate, being made
through the plate for the passage of air therethrough; the edges of the tablets will
then rest more or less on the inner ring 15 of the floor-plate. For a larger lamp
the floor-plate may have two or more concentric inner rings and the charge-
plate a corresponding number of concentric rings of tablet-containing holes (of
any desired capacity according to the size of the tablets employed) with intervening
air-holes. For producing pyro-betulin anhydride the floor-plate may advan-
tageously consist, as shown in plan in Fig. 9, of a metal ring 18 having opposite
sides connected together by a number of parallel bars 19 and the charge-plate may
consist, as shown in plan in Fig. 8, of a similar ring 20 having two intersecting
sets of bars 21 and 22 respectively, that connect opposite sides but are placed at a
comparatively great distance apart and between which the tablets are arranged near
together transversely to the bars 19 of the floor-plate. The tablet-containing
holes of the charge-plates, whether for producing pyro-betulin or for producing
Pyro-betulin anhydride, may be made with sinuous or serrated outlines so as to
prevent the checking of the extrication of the fumes that might otherwise occur
through the swelling of the tablets whilst burning, especially in the case of large
tablets. The lamp is provided with a chimney 23 of wire gauze, which rests on
and within a collar 24 secured to the cup 9. Besides acting as a support to the
chimney, the collar 24 serves to prevent air from entering the chimney 23 between
the latter and the cup 9 to any injurious degree.
In using apparatus constructed as described, the tablets, having been suitably

page_text: arranged in the lamp as hereinbefore described, are ignited simultaneously by
means of a jet or jets of gas caused to play upon their upper surfaces, and
any flame produced having been extinguished, the chimney 23 is placed upon the
cup 9 and the lamp put upon its stand 8. The conical cover 4 is then placed in
position, whereupon the fumes, on being formed, rise upwards to the top 25 of
the cover 4, which deflects them downwards and causes them to descend into the
chamber 1, upon the floor of which they become deposited; the thickness of the
deposit thus formed-it may be by a succession of charges-will, of course, depend
on the quantity of the substance required. It is advisable that, especially in
cold weather, the lamp and its charge should, when arranged for producing
Pyro-betulin anhydride be preparatorily heated as much as consistent with its
proper handling, in order more completely to prevent at the outset the evolution
of low-temperature fumes adapted to produce pyro-betulin. In the case of
chambers 1 of large area, apertures 26 and 27, normally closed by screw plugs,
as shown, are provided at opposite ends of the chamber 1, and after a charge has
been burnt and before igniting a new one, the cover 4 is removed and fresh air
pumped or blown through these apertures to displace the air that is no longer
capable of supporting combustion. Instead of providing the apertures 26 and 27,
or for use as an alternative thereto, there may be provided in each end wall of the
chamber 1 an aperture the entire width of the end wall, say about 2 inches in
height, and just clear of the bottom of the chamber, and furnished with a hinged
door. I have obtained satisfactory results with an apparatus as above described
in which the chamber 1 had a length of 22 inches, a breadth of 16 inches, and a
depth of 8 inches, whilst the opening 2 in its top was 9 inches in diameter, the
height of the cover 12 inches, and the diameter of the cup 9 of the lamp 24 inches,
this being adapted for small circular tablets of about 5 inch in diameter. With
this apparatus I have employed tablets to the full extent of the respective charge-
plates. The cover here described would be large enough for a chamber very
considerably larger than the one here referred to.
A chamber 1 of very large area should be provided with openings 2 (each with
its lamp stand, lamp and conical cover as described and shown in relation to the
single opening 2 of the example shown in the drawings) to the number requisite
for securing due circulation of air and evolution of fumes in each case. A hook.
or ring attached to each corner of such a chamber and connected with a common
rope or chain passing over an overhead pulley is convenient for raising the cham-
ber to allow of the removal of the deposited material from the floor of the
chamber. Furthermore, each conical cover of such a chamber 4 may be made
in two parts forming an air-tight joint with each other by means of flanges, the
lower part supporting the stand for the lamp, and each part having one or more
internal annular grooves or corresponding annular projections forming channels-
adapted to prevent condensed moisture from running down and falling upon the
deposited pyro-betulin or pyro-betulin anhydride.
For reducing the epidermis of birch-bark to a sufficiently fine powder for use
in the tablets,. I first pass it in a dried state through a disintegrator until it is
reduced to a finely shredded condition; I then additionally dry it by exposing
it to the air freely and to a temperature of 160° F. during three days: and I then
pass it repeatedly under very large and heavy stone edge-runners until sufficiently
fine to pass through a sieve having sixty holes to the linear inch.
When betulin-containing material made as set forth is burnt under the con-
ditions hereinbefore described, the cortical matter surrounding or enclosing the
betulin becomes, by contact with the burning zone, heated to such an extent
that, aided by the current of air, produced by the heat of combustion, it volati-
lizes the betulin. When the tablets are arranged near together so as to give a
limited air-supply the temperature of combustion and relatively long heat-
ing are such as to eliminate more or less completely a molecule of water and thus
to produce pyro-betulin anhydride, but when the tablets are so arranged as each
to have an abundant air-supply the temperature of combustion is too low and the

page_text: evolution of the fumes too rapid to effect this elimination, with the result that
pyro-betulin itself is deposited upon the floor of the chamber.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed, I wish it to be under-
stood that I do not claim the production of coatings of films of pyro-betulin or
Pyro-betulin anhydride on articles or materials, such production, being claimed in
the Specification of Letters Patent No. 12017 of 1897, but I declare that what
I claim is:
1. The manufacture or production of certain substances which I term pyro-
betulin and pyro-betulin anhydride in forms other than that of films by burning
in closed chambers, without flame, and in currents of air, material made from
birch bark and containing betulin to amounts bearing suitable ratios to the
capacities of the said chambers.
2. The manufacture or production from birch bark of certain substances which
I term pyro-betulin and pyro-betulin anhydride, substantially as set forth.
בד
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.