Improvements relating to the Production of Light by the Incandescence of Refractory Materials.
Year: 1886

page_text: The decision of the Chief Examiner, acting on behalf of the Comptroller, of the
18th day of September 1895, allowed, under Section 18 of the Patents, &c.
Act, 1883, an Amendment of this Specification.
Date of Application, 1st Sept., 1886
Complete Specification Left, 1st June, 1887-Accepted, 1st July, 1887
PROVISIONAL SPECIFICATION.
Improvements relating to the Production of Light by the
Incandescence of Refractory Materials.
We FREDERICK LAWRENCE RAWSON and WILLIAM STEPNEY RAWSON both of
11 Queen Victoria Street in the City of London Electrical Engineers do hereby
declare the nature of this invention to be as follows:-
This invention relates to improvements in the manufacture of mantles and apparatus
connected with the production of light by means of incandescence of refractory
materials known as the Welsbach Incandescence Light.
It is found that it is of the utmost importance that the mantles which are to be
rendered incandescent by the Bunsen burner should be as regular as possible in their
contour and also should be slightly conical in shape so as to allow the flame to play
evenly upon their surface.
This is effected by stretching them upon a platinum mandril previous to ignition
and after lighting them from above and allowing them to smoulder down slowly we
play a blowpipe flame upon them with gradually increasing force so as to compel
them to take the exact shape of the mandril which may be previously moulded to any
desired form.
By these means the mantles are also raised to their full efficiency at once which
would otherwise require four or five hours burning over the usual Bunsen flame.
The mantles having thus been given their proper shape at a higher temperature
than they will afterwards be raised to are less likely to lose their shape and therefore
their efficiency.
Difficulty has been found heretofore in the transport of these mantles without
breakage and various methods have been proposed. This difficulty may be overcome
by dipping the mantle after ignition into a liquid which will thoroughly penetrate the
pores of the material and will afterwards set to such a degree of hardness as to protect
the material from danger of breakage in packing or handling and which can afterwards
be removed without leaving any objectionable residue.
We have found that a very satisfactory method consists in dipping the cone into a
hot solution of volatile hydrocarbon mixed with paraffin wax or of paraffin alone; by
this means the mantle is covered with a thin coating of wax which becomes sufficiently
hard on cooling to allow of packing and handling without fear of breakage. The
paraffin being capable of burning away without any residue except carbon, which will
always be burned completely away by the flame of the Bunsen burner. It is quite
easy to ignite the mantle from the top previous to placing it into position over the
burner and allowing it to burn down, which it does somewhat after the fashion of a
candle and leaves no residue prejudicial to the light giving properties of the mantles.
We prefer to use a high-boiling point paraffin such as ozokerit and dip the mantle

page_text: into it while at a high temperature. By these means only a small quantity is left on
the mantle but quite sufficient to protect it satisfactorily.
We may also afterwards suspend the dipped mantles in a hot air bath and remove
all unnecessary paraffin which adheres between the meshes of the net; this runs
slowly to the bottom of the mantle where it can be taken off by absorption with
blotting paper or by like means.
We find that quite sufficient paraffin then remains in the pores of the netting to
project it from injury.
We find also this method of treatment to be of service in the preparation of mantles
previous to ignition, for a definite shape may be given them by dipping them while
extended over a former, and we find that in burning the paraffin serves the purpose of
helping to keep that shape without distortion, thereby ensuring greater symmetry and
consequent increase of light when the mantle is placed over the burner.
Other materials may be employed but we find that paraffin which can be obtained
very pure is the least sticky and leaves less residue than any of the others.
It also serves to protect the mantle from dust which is of great harm to it for the
dust which may adhere to the paraffin wax is entirely carried away when the paraffin
is burnt.
Instead of the usual mode of attachment by suspending the mantle from two fixed
points which allows of considerable movement and consequent danger of breakage of
the mantle it is preferred to attach it to three points symmetrically placed round a
ring to ensure greater rigidity.
To effect this easily a platinum wire is inserted through the whole circle of a thick
hem at the top of the mantle leaving the ends free so as to form one attachment
and two other platinum wires are passed round this ring of platinum wire so as to
form the other two attachments in this way no strain is put upon the fragile substance
of the mantle.
The ring to which these wires are attached is preferably slotted on its upper side
with three pairs of slots close together and symmetrically placed round the ring and
wide enough to admit the two wires twisted together.
These wires are passed into one slot then round the ring support and over again
through the other slot after which the wires may be cut flush with the outside of the
ring without fear of loosening and so a neat attachment made with no projecting ends
the movement of which is apt to alter the position of the mantle.
The gallery or support for the chimney carries a screw attachment for the wire
support of the mantle and it is preferred to make this attachment in such a way that
it allows of a small horizontal variation in the position of the mantle in addition to the
usual vertical movement so as to cause the latter to hang exactly vertically over the
burner without bending the wire support. This may be done by stamping a piece of
brass plate into small corrugations close to each other and large enough to receive the
wire support one end of the plate being rivetted to one of the gallery supports and
the pressure on the other end being regulated by a thumb screw.
The wire support
is then inserted into that semi circular corrugation which enables the mantle to hang
exactly in the right position. The spring of the plate prevents the support slipping
suddenly down when the thumb screw is loosened which would lead to the breakage
of the mantle on the top of the burner.
The usual gallery is dispensed with on account of its interference with the light
immediately below the burner and a support of as skeleton a nature as possible is
employed.
We find the position of the chimney to be of great importance and where as it has
been the custom to place it so that its lower edge is one or two inches below the top
of the burner, the gallery should be constructed so that the chimney is supported with
its edge flush with the top of the burner.
This increases the temperature of the burner so that an increase of from 10 to
20 per cent. takes place in the light emitted by the mantle and this increase found
more marked when the pressure of gas is low than when it is high but in all cases a
substantial increase takes place.

page_text: The burner has a small pin inserted just above the shoulder upon which the gallery.
rests and a slot is cut in the ring in the gallery encircling the burner so that by a sort
of bayonet joint the burner and gallery can be firmly locked together and thus ensure
a firm support for the glass work above as well as rigidity in packing for travelling.
As it is very important that the flame shou'd issue exactly vertically from the burner
and as it is found that a considerable proportion of gas fittings are so constructed that
when the burner is screwed upon the nipple it is not exactly vertical and therefore
causes the flame to issue otherwise than vertically. It is preferred to attach to the
gas nipple a bell socket or other form of joint which can be turned so that its nipple
is exactly vertical-it is then firmly screwed into this position and the burner with its
mantle and glass work is screwed on to this nipple instead of the original gas thread
and the whole apparatus is then in the proper position for giving its full efficiency.
Any subsequent movement of the gas bracket or arm can be easily corrected by
loosening the screw of the joint and resetting the apparatus vertically.
For chimneys it is preferred to use what is called frosted glass as being the best
adapted to diffuse and modify the intense light with a minimum of absorption. The
reflection from the back of the chimney largely compensates for the absorption in
front so that the total loss does not exceed 9-15 per cent. of the light passing through
a plain glass chimney.
Dated this 1st day of September 1886.
CARPMAEL & Co.,
Agents for the Applicants.
Improvements relating to the Production of Light by the
Incandescence of Refractory Materials.
We, FREDERICK LAWRENCE RAWSON, and WILLIAM STEPNEY RAWSON, both of
11 Queen Victoria Street, in the City of London, Electrical Engineers, 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 :-
This invention relates to improvements in the manufacture of mantles and apparatus
connected with the production of light by means of incandescence of refractory
materials known as the Welsbach Incandescence Light.
It is found that it is of the utmost-importance that-the-mantles which are to be
rendered incandescent by the Bunsen burner should be as regular as possible-in-their
contour-and-also should be slightly conical in shape so as to allow the flame-to-play
evenly upon their surface.
This is effected by stretching them upon a platinum mandril previous to ignition
and-after lighting them from above-and allowing them to smoulder down slowly we
play a blowpipe flame upon them with gradually increasing force so as to compel them
to-take-the-exact shape of the mandril which may be previously moulded to any
desired-form:
By-these-means-the-mantles-are-also-raised to their-full-efficiency at once-which
would otherwise require four or five hours burning-over the usual-Bunsen flame.
The mantles having thus been given their proper shape at a higher temperature
than-they will-afterwards be raised to are less likely to lose their shape and therefore
their efficiency:
The platinum foil should be of just-sufficient-thickness to keep its shape which can
always be renewed by smoothing out upon a former. The heat of the blow pipe will in
this way be more easily kept up-and-not-lost by the cooling of the metal. The
manties may be-stretched-and-treated upon the mandril-either before or after they are
attached to-the-upright which supports them-in-the-finished-lamp:

page_text: Difficulty has been found heretofore in the transport of these mantles without
breakage and various methods have been proposed. This difficulty may be overcome
by dipping the mantle after ignition into a liquid which will thoroughly penetrate the
pores interstices of the material and will afterwards set to such a degree of hardness as
to protect the material from danger of breakage in packing or handling and which can
afterwards be removed without mechanical injury to the mantles or without leaving
any objectionable residue.
We have found that a very satisfactory method consists in dipping the cone into a
hot solution of volatile hydrocarbon mixed with paraffin wax or of paraffin alone; by
this means the mantle is covered with a thin coating of wax which becomes
sufficiently hard on cooling to allow of packing and handling without fear of breakage,
the paraffin being capable of burning away without any residue except carbon,
which will always be burned completely away by the flame of the Bunsen burner.
It is quite easy to ignite the mantle from the top previous to placing it into position
over the burner and allowing it to burn down, which it does somewhat after the
fashion of a candle and leaves no residue prejudicial to the light giving properties of
the mantles.
If preferred the mantle can be ignited when fixed in its position over the burner
before lighting the gas at the mouth of the burner.
We prefer to use a high boiling point paraffin such as ozokerit and dip the mantle
into it while at a high temperature. By these means only a small quantity is left on
the mantle, but quite sufficient to protect it satisfactorily.
We may also afterwards suspend the dipped mantles in a hot air bath and remove all
unnecessary paraffin which adheres between the meshes of the net, this runs slowly to
the bottom of the mantle where it can be taken off by absorption with blotting paper
or by like means.
We find the following a suitable plan for combining the paraffin with the mantle.
The paraffin is kept at a suitable temperature in a glass cylinder resting in a metal
cylinder closely fitting it and containing oil which can be raised to a high temperature
without giving off vapour.
The mantle is then dipped into the paraffin and being slowly withdrawn the greater
part of the paraffin runs off and the only part holding an excess of paraffin is the
lower edge. This excess is best removed by wiping with a warm piece of glass down
which the paraffin will run. While the lower edge is still pliable and before the
paraffin has hardened we find it advisable to give the requisite shape to the mantle by
carefully moulding it over the rounded end of a glass test tube of the right
dimensions. Thus the mantle assumes a perfectly rounded shape when the paraffin
sets hard.
We find that quite sufficient paraffin then remains in the pores interstices of the
netting to protect it from injury.
We find also this method of treatment-to-be of service in the preparation
of mantles previous to ignition but after they have-been-impregnated, for-a-definite
shape-may be given them by dipping-them-while-extended-over-a-former,-and-we
find that in burning the-paraffin-serves the purpose of helping-to-keep-hat-shape
without-distortion, thereby ensuring greater symmetry-and-consequent increase of
light when the mantle is placed over-the-burner-
Other materials may be employed as long as they set hard at ordinary temperatures
and burn away without mechanical destruction to the mantle and without leaving any
residue which would injure the light giving properties of the mantle, but we find that
paraffin which can be obtained very pure is the least sticky and leaves less residue
than any of the others.
It also serves to protect the mantle from dust, which is of great harm to it for the
dust which may adhere to the paraffin wax is entirely carried away when the paraffin
is burnt.
Instead of the nonal-mode-of-attachment-by-suspending the-mantle-from-two
fixed points which allows of considerable movement and consequent danger of

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three or more points
symmetrically placed placed-round a ring to secure greater rigidity..
To-effect-this-easily a platinum wire is inserted-through the whole-circle-of-a
thick hem-at-the-top-of-the-mantle leaving the ends free so as to-form-one-attach-
ment and two or more-other-platinum wires are passed round this-ring-of-platinum
wire so as to form the other-attachments, in this way no strain is put upon the
fragile substance of the mantle.
The ring to which these wires are attached is preferably slotted on its upper side
with three-or-more-pairs of slots close together-and-symmetrically placed round
the ring and wide-enough-to-admit the two-wires twisted-together.
These wires-are-passed-into one slot then-round-the-ring-support and over-again
through the other-slot-after-which the wires may be eut flush with the outside of the
ring-without-fear of loosening and so a neat attachment-is-made with-no-projecting
ends the movement of which is apt to alter the position of the mantle.
The gallery or-support for the chimney carries a serew attachment for the wire
support of the mantle and it is preferred to make this attachment in such a way that
it allows of a small horizontal-variation in the-position of the mantle in addition
to the usual vertical movement-so-as to cause the latter to hang exactly-vertically
over the-burner-without bending-the-wire-support. This may be done-by-stamping
a piece of brass plate into small corrugations close to each other-and-large-enough
to-receive-the-wire-support-one-end-of the-plate being rivetted-to-one-of-the-gallery
supports and the pressure on the other end-being-regulated by a-thumb-serew.
The-wire-support-is-then-inserted into that semi-circular-corrugation which-enables
the-mantle to hang exactly in the right position. The spring of the plate prevents
the-support slipping suddenly down when the thumb-serew is loosened which would
lead to the breakage of the mantle on the top of the burner.
The usual gallery is dispensed with on account of its interference-with-the-light
immediately below the burner and a support of as skeleton-a-nature as possible
is-employed.
We find the position of the chimney to be of great importance and whereas it
has-been-the-custom to place it so that its lower edge is one or two inches below
the top of the burner the gallery should be constructed so that the chimney-is
supported with its edge flush with the top of the burner.
This increases the temperature of the burner so that an increase of from 10 to
20 per cent. takes place in the light emitted by the mantle and this increase is
found more marked when the pressure of gas is low-than when it is high but-in-all
eases-a substantial increase takes-place.
We prefer to use below the chimney a glass ring separated from-the-chimney
by-about-th of an inch. This ring does not interfere with the light and prevents
any accidental fracture of the mantle by matches or tapers being pushed against it
in-the-net-of lighting the lamp.
The cone shaped portion of the gallery is perforated with holes of a suitable
size-to-allow-the-flame of a match-or taper to ignite the lamp without the necessity
of pushing it far enough to endanger-the-mantle.
The burner has a small pin-inserted just above the shoulder upon which the
gallery rests and a slot is cut in the ring in the gallery eneireling the-burner-so-that
by-a-sort of bayonet-joint the burner-and-gallery-can be firmly locked-together and
thus ensure-a-firm support for the glass work above as well as rigidity in packing
for travelling.
As it is very important that the flame-should issue exactly vertically from the
burner and as-it-is found that a considerable-proportion of gas fittings-are-so-con-
structed that when the burner is serewed upon the nipple it is not exactly-vertical
and therefore-causes the flame to issue-otherwise than vertically, it is preferred to
attach-to-the-gas-nipple a ball and socket or other form of joint which can be turned
so-that-its-nipple is exactly vertical-it is then firmly serewed into this position
and the burner with its mantle and glass-work-is-serewed on to this nipple instead

page_text: of the original gas thread and the whole apparatus is then-in-the-proper position-for
giving its-full-efficiency.
Any subsequent movement of the gas bracket or arm can be easily corrected-by
loosening the serew of the joint and resetting the apparatus vertically:
For chimneys-it-is-preferred to use what is called frosted glass as being the best
adapted to diffuse and modify the intense light with a minimum of absorption. The
reflection-from-the back of the chimney largely compensates for the absorption in
front-so-that-the- total loss does not exceed 0 15 per cent. of the light-passing
through-a-alain class chimnov
which the lamp is preferably lighted.
Figure 2 is a section on the line X X Figure 1 shewing one spring holder-D-for
the upright-support of the mantle.--This-holder is tightened on the upright by means
of the serew E. F is the pin-which-locks-together-the-burner and gallery while-G
is the slet-through which the pin passes-when-the-gallery is slipped on to the burner:
Figure 3 shows another method of forming the spring holder with corrugations in
the spring plate D so as to allow of horizontal adjustment of the upright.
Figure 4-shows-a-ball and socket joint for supporting the burner. The burner-is
serewed on to the thread H. The thread I may be of any suitable size for serewing
on existing fittings.
A lead washer K with a hole in the centre-through-which the gas passes is placed
between the ball and the socket so that by tightening the screw of the cap L the whole
is made into one rigid support for the lamp the moveable ball portion being set at any
required angle with the lower part to ensure the-burner being-vertical.
To avoid the likelihood of the movement of the ball its lower surface is grooved-se
that the compression of the cap may cause it to hold more firmly to the washer which
penetrates the-recesses of the grooves.
Figure 5 is a vertical-section and Figure 6 is a plan showing to twice-the-natural
seale-the arrangements for attaching the mantle to the top-of the-support. -M is the
ring to which the hood is attached. Its ends are twisted together as shown at N
Figure 6 and are-secured by being wound round the ring O entering slots in its top
as shown in Figure 5: -PP are separate-wires-secured in a similar way.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is :-
1. The method of treating the mantles of refractory materials with a blow-pipe
Home substantially as described.
2. 1. The treatment of the mantles after ignition by immersion in a liquid which will
afterwards set and will burn away without prejudicial results to the mantles for the
purposes set forth.
3. 2. The use of paraffin substantially as described in the treatment claimed under the
second first claim.
4. The process of shaping-the-mantles before ignition by immersion-in-paraffin-or
other-liquid-which-will afterwards set substantially-as-described.
5: The-method-of attachment-of-the-mantle-to-the-upright-support-substantially as
described.
6. The method of fastening-the-upright-to-the-gallery-substantially as described.
7-The-combination of a burner of this class with a gallery-such as-will-support
the chimney so that its lower end is approximately at the same level as the top of the
burner substantially-as described.
8. The method of attachment of the gallery to the burner substantially as described;

page_text: 9. The use of a ball and socket or other adjustable-joint to carry the-burner so that
it can readily be set in a vertical-position-substantially as described:
Dated this 1st day of June 1887.
CARPMAEL & Co.,
Agents for the Applicants.