Improvements in, and connected with Ovens for Baking or Heating Porcelain and other Substances for Dental and other Purposes.
Year: 1896

page_text: Date of Application, 19th Mar., 1896
Complete Specification Left, 10th Dec., 1896-Accepted, 6th Mar., 1897
Improvements in, and connected with Ovens for Baking or
Heating Porcelain and other Substances for Dental and other
Purposes.
I, WILLIAM DALL, of 8 Newton Place, Glasgow, Surgeon Dentist, do hereby
declare the nature of this invention to be as follows:-
This invention relates to ovens for baking or heating porcelain and other
substances for dental and other purposes and it has mainly for its object to so
improve the construction of the oven that an equable heat will be given to the
substance or substances under treatment. The invention also comprises other
improvements.
In carrying out my invention I make the oven with an outer and, preferably,
cylindrical casing which is provided with a flame inlet in its bottom and with a
canopy or dome cover at top. Fitted removably within the casing is a muffle
which is closed by a lid on top. This muffle is provided with supporting lugs
or projections which rest on a ledge or ledges in the interior of the casing.
The cover is provided with a telescopic chimney which is supported by a bar or
bracket. The cover may be balanced by means of suitable counterpoise weights
and chains so as to be easily raised and lowered.
The muffle is, or may be, provided with a lateral extension in which a glass, mica,
or other transparent medium is fitted so as to enable the contents of the muffle to
be observed during treatment. The transparent medium may consist of a
magnifying lens which can be coloured if desired.
With this construction of oven the flame or flames play all round the muffle and
heat its contents equally. When the substance under treatment is sufficiently
baked, which can be observed through the small window or lens, the cover is
raised up and the lid of the muffle removed so that the substance can be
withdrawn.
The oven is preferably heated by gas and in this case a compound burner is used
which consists of a pipe with a bell mouth and a blow pipe branch at the side.
The pipe is fitted to or made one with a gas tap having two passages of different
diameters in its plug, the large passage being opened when it is desired to have a
full flow of gas to produce a yellow or blow pipe flame and the small passage when
it is desired to have a reduced flow of gas in order to produce a Bunsen flame.
Above the tap an air inlet is provided which is capable of being closed by a
sliding ferrule. A second regulating tap is fitted below the two way tap. The
blow pipe branch has also by preference a tap fitted on it.
The Bunsen passage in the plug of the two way tap may consist of two or more
small holes.
Dated 10L 1
1000
H. D. FITZPATRICK,
70 Wellington Street, Glasgow, Agent.

page_text: Improvements in and connected with Ovens for Baking or
Heating Porcelain and other Substances for Dental and other
Purposes.
1, WILLIAM DALL, of 8 Newton Place, Glasgow, Surgeon Dentist, do
hereby declare the nature of this invention and in what manner the same is to
he performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to ovens for baking or heating porcelain and other
substances for dental and other purposes and it has mainly for its object to so
improve the construction of the oven that an equable heat will be given to the
substance under treatment. The invention also comprises improvements in the
burner.
And in order that my said invention may be properly understood I have here-
unto appended two explanatory sheets of drawings, whereon,
Fig. 1 is a perspective view of the oven.
Fig. 2 is an enlarged sectional view of the oven.
Fig. 3 is a front elevation and Fig. 4 a vertical section of the burner.
Fig. 5 is a front elevation and Fig. 6 a vertical section of a modified construction
of the burner.
+--
Fig. 7 is a sectional detail.
In carrying out my invention I make the oven with an outer and, preferably,
cylindrical casing a which is or may be fitted in a pedestal b placed on the table or
bench c. The casing is provided with a cover or canopy d having a short chimney e
which works telescopically in the flue pipe. The cover d may be adjustably held in
place by means of counterpoise weights y attached to chains h which pass over the
pullies i secured to the flue. In Fig. 1 the cover is shown as raised up whilst in
Fig. 2 it is shown as lowered down on top of the casing a.
a and the
An opening is made eccentrically through the bottom of the casing
pedestal for the gas burner, which, when fitted in place, is therefore out of
the centre of the casing being somewhat nearer to the front of the oven than
the back.
Fitted removably within the casing a is a muffle k made of platinum or other
suitable material and closed by means of a removable lid k. This muffle is
provided with supporting lugs which rest upon recessed ledges k³, or equivalent,
made in the casing a. As will be seen an annular space is left all round the
muffle for the hot products of combustion to pass upwards from the burner and
between the lugs to the chimney e.
The muffle is, preferably, provided with a lateral tubular extension m which fits
into the peep hole m' made in the walls of the casing. The peep hole is preferably
provided with a cap m² (shown in dotted lines Fig. 2) having a window m made-of
mica or other suitable and well known transparent medium, or, if desired, it may
be provided with a magnifying lens which can be coloured if so desired. The
contents of the muffle can be easily observed through the peep hole from time to
time during the treatment. If desired the window m³ can be fitted in the
extension m of the muffle.
If desired a mica pane may be fitted in a peep hole (Figs. 1
the walls of the casing a for observing the flame.
and 7)
made in
With this construction of oven the flame or flames play all round the muffle and
heat its contents equally. When the substance under treatment is sufficiently
baked, which can be observed through the small window or lens, the cover is

page_text: raised up and the lid of the muffle removed in order that the substance may be
withdrawn.
The oven is preferably heated by gas, and, in this case, a compound burner of
novel construction is used, which consists' of a pipe o (which may be screwed
externally) provided with a head' p which has a bell mouth or tapered passage pl
in it. The passage is covered by wire gauze or a perforated plate p². A lateral
blow pipe branch is inade or fitted in the pipe o just above the air inlet of the
Bunsen burner s. This branch, which is provided with a regulating tap, is
connected by an india rubber or other pipe (y, Fig. 1) with a bellows or other
suitable air compressing or forcing device. The air openings of the Bunsen can be
closed, whenever desired, by means of a sliding ferrule or ring shutter t provided
with handles t¹. I
The pipé o is fitted to or made one with a gas tap having two passages u', u',
in its plug at right angles to one another. The small passages u are formed by
merely drilling holes through the plug.. When it is desired to have a full flow
of gas to produce a yellow or blow pipe flame the tap u is turned so as to open the
large passage u and when it is desired to have a reduced flow of gas for a Bunsen
flame the tap is turned so as to open the passages u³. A second regulating and cut
off tap is fitted below the tap u.
In the modification of the burner shown at Figs. 5 and 6 the pipe o is screwed
externally and is provided with a nut y for clamping the burner in place in the manner
shown at Fig. 2. In this case the sliding ferrule is replaced by a partially
revolving ring-shutter t provided with openings to and handle t'. In lieu of the
arrangement of taps u, v, shown at Figs. 3 and 4, the pipe o has an extension o¹
fitted to its lower end by means of the screwed nipple o' and this extension is
provided with a single tap u having two ways u¹ u in it as shown at Fig. 6 where
it will be seen that the tap is so turned as to supply gas to the small passage w¹
and pipe wo for producing a Bunsen flaine. When the plug is turned so that the
passage u is in the vertical position a full supply of gas is given for a blow pipe or
yellow flame. By turning the plug half round the gas can be cut off.
In this modification of the burner the small passage w' and pipe w take the
place of the small holes u of the tap u Figs. 3 and 4. The part of of the burners
Figs. 3 to 6 is connected by an india rubber or other pipe y' (Fig. 1) with the gas
supply.
The air supply of the Bunsen can be turned on or off or regulated as desired by
merely manipulating the ring t.
The blow piper being arranged, as shown, causes the air jet to strike directly
against the inner wall of the pipe o and as a consequence to be broken or spread
out. By thus breaking the jet not only is a better admixture of the gas and air
obtained but the noise produced by the burner is very much lessened.
If desired the muffle k may have a rim or the like and be supported by projections
in the casing a.
It is obvious that the details of construction of the burner and the arrangement
of the oven can be modified without departing from the invention.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed 1 declare that what
1 consider novel and desire to claim is :-
1. An oven for baking or heating porcelain or other substances for dental or
other purposes having a muffle (such as k) supported concentrically within it by
means of lugs or their equivalent so that the products of combustion from the
burner can pass freely all round the muffle and heat its contents equally, substan-
tially as herein before set forth.
2. In combination, the casing, the muffle supported within the casing by means
of projecting lugs or their equivalent, a lateral extension made in the muffle and
means, such as a mica window or a lens, for observing the contents of the muffle
through the extension, substantially as hereinbefore set forth..

page_text: 3. The compound burner for heating purposes having a lateral blow pipe
branch (r) or its equivalent situated between the Bunsen and the mouth of the
burner, substantially as herein before set forth.
4. In combination, the pipe o, the lateral blow pipe branch secured thereto, the
Bunsen 8, means, such as a ring t, for opening or shutting off the air supply to the
Bunsen, and a regulating gas tap, such as u, substantially as herein before described
with reference to the drawings annexed.
5. The general arrangement and combination of parts of the muffle oven
substantially as hereinbefore described and shown at Figs. 1 and 2 of the drawings
annexed.
Dated this 8th day of December 1896.
H. D. FITZPATRICK,
70 Wellington Street, Glasgow, Agent.