Improvements in and connected with Furnaces.
Year: 1893

page_text: Date of Application, 2nd Aug., 1893
Complete Specification Left, 2nd May, 1894-Accepted, 2nd Aug., 1894
PROVISIONAL SPECIFICATION.
Improvements in and connected with Furnaces.
JOHN HUTCHENS GARTRELL, Dentist 47 Chapel Street, Penzance, Cornwall,
do hereby declare the nature of this invention to be as follows :-
The object of this invention is, the production of an intense heat by the com-
bustion of petroleum spirit vapour under pressure for the "firing" of porcelain
used in the construction of artificial teeth and palates and for various operations in
the arts and sciences where an intense heat is required. The vapour is produced
and the pressure maintained without the use of pumps, footblowers fans or the
pressure obtained by returning some of the vapour to the tank. The apparatus is
described in the following statement.
A pressure tank is made of copper or any other suitable metal to hold the
petroleum spirit. A convenient size is made from copper tube five or six inches
diameter and twelve or fourtecu inches long by of an inch thick.
This is made
into a pressure tank by screwing a gun metal bottom and top upon the ends. To
the top or cover is secured a brass union and valve to connect the tank to the water
service of the town. The tank is also fitted with a piston of brass having a
cupped leather packing. To the piston is attached a brass tube about of an inch
in diameter and thick which passing through a gland in the centre of cover
acts as a guide rod. Through this tube also the tank is filled with petroleum spirit a
screw stopper being fitted to the top for this purpose. Pressure is produced upon
the piston by turning the valve and letting in the water which forces down the
piston upon the petroleum spirit. To the bottom of this tank is fitted a fluid tap
and to this tap is secured a small copper tube the diameter of bore being in
proportion to the size of the apparatus and commencing at inch for the smaller
sizes. This tube conveys the petroleum spirit under pressure to the vaporiser and
blast tube. The vaporiser is similar to those that have been in use for some years-
but the blast tube is improved by shaping it to admit of more air entering the tube
with the spirit vapour. Also by casting a tray or pan in one piece with the
vaporiser and blast tube to catch the fluid escaping from the nozzle when the
tap is opened for the preliminary heating of the vaporiser the blast tube is also
shaped to give a flat flame instead of a circular one, a flat flame being more
suitable for heating a muffle furnace. In firing porcelain or the process known
among dentists as continuous gum
work" the work is placed in a' muffle in a
fireclay furnace that has an opening in its side to allow of the flame from the blast
tube being injected under the muffle by the pressure of the water in the tank acting
through the piston upon the petroleum spirit and vapour.
The flame rises round
the muffle and the products of combustion escape through a hole in top of the
furnace. The most important novelty in the furnace is the muffle which is made of
nickel containing an alloy of two to three per cent. of ferro-manganese and silicon.
The fusing point of the above metal being very much higher than the fusing point
of porcelain the nickel muffles can be used very successfully for firing the work
without danger of cracking and admitting into the muffle the gases formed by the
combustion of the vapour. The liability of the ordinary fire clay muffles to crack
and ruin the work has caused a search for a better material for muffles and this
has been found in nickel and the alloy mentioned. These muffles are cast in sand
moulds to any shape or size but not less in thickness than 1% of an inch. To
indicate the heat in the muffle I use a piece of nickel plate bent to the shape of
the letter U and having a hole in one of its sides to support a bit of fine gold wire
which is placed in the muffle-close to the work. The melting of the gold wire

page_text: indicates the fusing point of the porcelain. The " firing" is then stopped by
closing the tap at bottom of tank and cutting off the supply of petroleum spirit to
the vaporiser. The tank containing the petroleum spirit may be placed in any
convenient position away from the vaporiser and above or below it. It will also
supply the spirit under pressure to one or more vaporisers and blast tubes at the
same time.
The apparatus will work successfully at any pressure above 15 ds. obtained
from the water supply of the town. To re-fill the tank with spirit the piston is
pulled up to the cover by a screw fitted to work through the centre of guide rod-
this screw is the same length as the traverse of the piston and is held in position to
pull up the piston by a bracket made of cast iron. A tap fitted to one side of the
cover carries off the water from the tank.
Dated this the 31st day of July 1893.
COMPLETE SPECIFICATION.
Improvements in and connected with Furnaces.
I, JOHN HUTCHENS GARTRELL, of 47 Chapel Street, Penzance, in the County
of Cornwall, Dentist, 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:―
The object of this invention is the production of an intense heat by the com-
bustion of petroleum vapour for the firing of porcelain used in the construction of
artificial teeth and palates and for various operations in the arts and sciences where
a powerful heat is required.
And in order that my invention may be thoroughly understood, I now proceed
to describe the accompanying drawing thereof, reference being had to letters and
figures marked thereon.
Fig. 1, is a front elevation of the apparatus arranged for heating a furnace.
Fig. 2, is a perspective view of the nickel muffle.
Fig. 3, is a side view of the pressure tank and fittings.
Fig. 4, is a vertical section of the pressure tank and fittings.
Fig. 5, is a front view of the vapourizer of burner.
Fig. 6, is a side elevation of burner.
Fig. 7, is a side and top view of indicator.
Fig. 8, is an end view of vapourizer and tripod stand.
Fig. 9, is cross vertical section on line A B of Fig. 6.
Parts of the figures are broken off for convenience.
The apparatus consists of a pressure tank c made of steel copper or any other
suitable material in various sizes, to hold the benzoline or petroleum. To the top
is secured a brass union and valve e and to the base of the tank I connect the
water service by a valve m to the supply. The tank c is also fitted with a glass
gauge or indicator d having a float which sinks in oil and floats on water a bit of
cork weighted with a tack answers for this purpose. A upper tube n is fixed on
top of the tank to the valve e. The tank is filled by unscrewing a stopper f fitted
to the top for this purpose. Pressure is produced upon the benzoline by opening
the valve m and letting in the water k which presses upwards the benzoline without
mixing with it water being the heavier fluid of the two. To the top of the tank
is fitted a valve e and to this valve e is secured a small copper tube n which conveys
the benzoline under pressure to the vapourizer b. An outlet tube g is provided at
the base of the tank. Figs. 5, and 6, are cast in one piece of iron and the
(shown by dotted lines) around the vapourizer band to the burner outlet 61 are
passages
drilled. Fitted to the burner outlet is a screw cone valve g for controlling the

page_text: power of the flame which discharges at this point. The blast can also be regulated
by the valve e on top of tank. The valves may be adjusted to each other to
prevent the blast burning in a jerky manner. The passages around the vapourizer b
are drilled through the holes at the end and at the top. These holes are stopped
with screw plugs such as r. Also the bottom of the vapourizer b has a hole
through for the benzoline to enter the said vapourizer and a stem 5 fitted to a
hole in the tripod this said stem revolves in the tripod stand; a gland in the tripod
stand packed with asbestos prevents the benzoline escaping around the stem
when under pressure.
A brass union u is attached to the tripod stand or base for
connecting the copper tube n. A preliminary heat is given to the burner by
opening the valves and allowing some oil to flow into the pan n' cast between the
nozzle n and burner outlet b¹ and applying a light. Also a rubber tube may be
attached to the tube v for using coal gas to heat the vapourizer.
It will be seen that the burner can revolve by means of the stem 6" upon the
tripod stand t whilst at work, a movement that is useful in brazing and similar
operations.
In firing porcelain or the process known among dentists as
"continuous gum
work" the work is placed in a muffle h inserted into an opening i in a fire clay
furnace a that has an opening in the side to allow of the flame from the burner
being injected under the muffle h which is the most important novelty in the furnace.
It is made of nickel containing an alloy of two to three per cent. of ferro-manganese
and silicon. These muffles are cast in sand moulds to any shape or size required.
To indicate the heat in the muffle I use a piece of nickel plate s bent to the shape
as in Fig. 7, and having a hole or holes in one of its sides to support a piece of
fine silver or gold wire which is placed in the muffle close to the work, the melting
of the silver wire indicates the fusing point of the porcelain.
The tank may be placed in any convenient position away from the burner and
will supply the benzoline or petroleum to one or more burners at the same time.
The apparatus will work successfully at any pressure above 7 lbs. and the pressure
may be obtained from the water supply of the town or by means of vapour
generated in the vapourizer of burner. To effect this a copper tube is secured
to one of the two plug holes at the nozzle end of burner and the other end of
copper tube attached by a union and valve to the top of tank, the vapour entering
the tank produces pressure upon the benzoline as in other apparatuses that are now
in use.
When using water to obtain the pressure a line o will indicate the division of the
benzoline and water in the tank. The water may be colored or a float used as
described to indicate this division.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a pressure tank, the combination of the pressure tank c inlet valve m
outlet g valve e screwed stopper f gauge glass d with float and the tube n to
connect to the tripod standi for supplying the vapourizer 6 and burner outlet b¹
with material, substantially as herein described and according to the accompanying
drawing.
2. In a furnace, the combination of a nickel muffle to fit in an opening i of the
furnace a, substantially as herein described and according to the accompanying
drawing.
3. Benzoline or petroleum vapourizers and burners on a tripod stand constructed
as herein described and illustrated in Figs. 6, 7, 8, and 9, of the accompanying
drawings.
J. P. BAYLY,
18, Fulham Place, W., Agent for the Applicant.