IMPROVEMENTS IN AND CONNECTED WITH ELECTRIC INCANDESCENT LAMPS
Year: 1881

page_text: "
LETTERS PATENT to George Guillaume André, of Dorking, in the County
of Surrey, for an Invention of IMPROVEMENTS IN AND CONNECTED WITH
ELECTRIC INCANDESCENT LAMPS."
PROVISIONAL SPECIFICATION left by the said George Guillaume Andre
at the Office of the Commissioners of Patents on the 24th October 1881.
GEORGE GUILLAUME ANDRE, of Dorking, in the County of Surrey.
"IMPROVE-
MENTS IN AND CONNECTED WITH ELECTRIC INCANDESCENT LAMPS."
The chief object of my Invention is the production of compact and dense durable
carbons of equal texture and without impairing or destroying the fibrous substance
from which I prefer to make them. Any vegetable fibre or fibrous substance, such
as rattan, may be used, and in order to adapt it to the purposes of my Invention
I submit the same to the action of nitric and sulphuric acid in the following
manner: The mixture preferred is one part of nitric acid to four parts of sulphuric
acid; the fibre is immersed therein from, say, twenty to thirty minutes, according
to circumstances, whereby it is converted into a material known as nitro-cellulose;
the material, nitro-cellulose, thus produced is then washed in order to remove the
acid therefrom and immersed in a solution of nitro cellulose in ether or alcohol, but
other solvents may be used if desired; it is there allowed to remain till it assumes
a semi-dissolved state, when it is removed and subjected to pressure; the material
thus prepared when dry is ready to be cut up or made or formed into the shapes
required. The shape which I prefer is that of an inverted double elongated or
inverted shape, preferably with a flattened base. I prefer to make the base flat to
facilitate the cutting out of the material, although any other shape wherein the
material is cut or formed out of one piece may be adopted. Single fibre or fibres
may be treated in the manner before described to produce the material aforesaid up
to its present stage, in which case the cutting is dispensed with, but care must be
taken when adapting it to the shapes required that the sides are kept parallel to
one another and that the bend only is at the end in order not to put tension on
any other part of the burner. I prefer to make the bend part more conductive than
the other. The material thus prepared is carbonized in the ordinary way and

page_text: treated with a solution of nitro-cellulose in ether or alcohol, or in tar, sugar syrup,
starch, and the like to fill up the pores; they are then calcined to carbonize the
absorbed substances, or the pores may be filled up by heating the carbon in a
vessel containing hydro carbon gas. I secure the carbon burner thus prepared in
the glass bulb by metal clamps in the ordinary way, or (which I prefer) I form
apertures in carbon blocks attached to the platinum wires which enter the bulb,
and into these apertures the carbon burner ends are placed; some nitro cellulose
or other material, such as lampblack and tar, is then placed in the apertures and
carbonized by passing the current through the blocks; for this purpose a wire is
connected to or abuts on the carbon blocks with a piece of metal between the two
carbon blocks, so as to pass the current transversely through the carbon blocks
without injuring the burner.
The carbonizing is effected in a jar or other vessel containing ordinary lighting
gas or other hydrocarbon gas.
Instead of the aforesaid mode of fixing the carbon burner to the platinum wires
I may place between the ends of same a strip or block of mica, talc, or other
insulating substance capable of withstanding heat, and I place the ends of the
platinum wires previously flattened out against the burner; another strip of mica
having been placed over the flattened wire I bind the whole together by means of
a metal clamp.
The burner having been placed in the globe I next proceed to form a vacuum
therein. Heretofore such exhaustion has been produced by means of a Sprengel
pump, which is a long, laborious, and at best incomplete method; I, on the contrary,
turn the globe or bulb upside down, pour mercury therein, and then by reversing
the position of the bulb I allow the mercury to escape, leaving behind a perfect
Torricellian vacuum, and seal up the lower tubular extremity of the bulb by
mears of the blow pipe in the usual manner. The bulb is fitted to a tube not
less than 31 inches in length to overcome the pressure of the atmosphere. This
method of exhausting is also applicable to all other lamps requiring a vacuum to
be formed in the bulb or globe.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Guillaume André in the Great Seal Patent Office on the
24th April 1882.
GEORGE GUILLAUME ANDRÉ, of Dorking, in the County of Surrey. " IMPROVE-
MENTS IN AND CONNECTED WITH ELECTRIC INCANDESCENT ELECTRIC LAMPS."
The chief object of my Invention is the production of compact and dense durable
carbons of equal or uniform texture, and without impairing or destroying the
fibrous substance from which I prefer to make them. Any vegetable fibre or
fibrous substance such as rattan may be used, and in order to adapt it to the
purposes of my Invention I submit the same to the action of nitric and sulphuric acid
in the following manner :-The mixture preferred is one part of nitric acid to four
parts of sulphuric acid; the fibre is immersed therein from, say, twenty to thirty
minutes, according to circumstances, whereby it is partially converted into a
material known as nitro-cellulose; the material, nitro-cellulose, thus produced is
then washed in order to remove the acid therefrom, and immersed in a solution of
nitro-cellulose in ether, or alcohol, but other solvents may be used if desired; it is
there allowed to remain till it assumes a semi-dissolved state, when it is removed
and subjected to pressure; the material thus prepared when dry is ready to he
cut up or made or formed into the shapes required. The shape which I prefer is
that of an inverted elongated shape, as shown at Figure 1 of the accompanying
Drawings, and preferably with a flattened base. I prefer to make the base or
bridge of the burner a flat, as shown at a¹, in order to facilitate the cutting out of
the material, although any other shape wherein the material is cut or formed out
of one piece may be adopted. Single fibre or fibres may be treated in the manner
before described to produce the material aforesaid up to its present stage, in which
case the cutting is dispensed with, but care must be taken when adapting it to the
shapes required that the sides are kept parallel to one another and that the
bend only is at the end, in order not to put tension on any part of the burner.
I prefer to make the bend part more conductive than the other.
The material thus prepared is carbonized in the ordinary way and treated with
a solution of nitro-cellulose in ether or alcohol, or in tar, boiled linseed, or other
drying oil, sugar syrup, solution of starch, dextrine and the like, to fill up the pores ;
they are then calcined to carbonize the absorbed substances, or the pores may be
filled up by heating the carbon in a vessel containing bydrocarbon gas; or instead
of this the filament may be steeped in boiled linseed or other drying oil and left to
dry, that is for the oil to become oxidized before calcining. This method of
treating the filament may also be used with advantage before carbonizing and in
connection with threads of fax or china grass, the action of the oil being to
cement the fibres together and to give an even or compact surface. The oil must be
fully dried or oxidized before carbonizing; or I use burnt boiled linseed oil mixed
with lamp black; in fact, the material or mixture formerly used, or printer's ink,
and I rub it into the fibre and then draw the latter through a round hole to
remove the superfluous adhering material; I then thoroughly dry or oxidize as
before.
I secure the carbon burner thus, or otherwise prepared in the glass bulb by metal
clamps in the ordinary way; or, which I prefer, and as shown at Figure 2, I form
apertures in carbon blocks b, or metallic sockets attached to the platinum or copper
wires c, c, which enter the bulb, and into these apertures the carbon burner ends
are placed, some dissolved nitro-cellulose, or wood, or paper pulp, or other material,
such as lamp black and burnt boiled oil, or tar or sugar syrup is then placed in

page_text: the apertures and carbonized by passing the current through the blocks; for this
purpose a wire d, d, is connected to or abuts on each of the carbon blocks b, with
a piece of metal e between the two carbon blocks b, so as to pass the current
transversely through the carbon blocks without injuring the burner, or the heating
may be effected by the blow-pipe, care being taken to protect the filament end from
combustion.
The carbonizing by the electric current is effected in a jar or other vessel
containing ordinary lighting gas or other hydrocarbon gas to prevent the filament
from being burnt. The deposition of carbon from the gas improves the contact
between the block and the filament.
Instead of the aforesaid mode of fixing the carbon burner to the platinum wires
I may, as shown at Figure 3, place between the ends of same a strip or block ƒ of
mica, talc, or other insulating substance, such as steatite, capable of withstanding
heat, and I place the ends of the platinum or copper wires c, previously flattened
out against the ends of the burners a, another strip of mica g baving been placed
over the flattened wire on one side (or it may be on both) I bind the whole
together by means of a metal clamp or clip h.
Or according to a modified arrangement, as shown at Figure 4 and Figure 5,
I use a block f formed with a groove in each side, as shown in plan at Figure 5,
and I place the ends of the burner a and the ends of the wires c in the said grooves,
which are then filled with a carbon paste, and I then brush over this part with a
cement such as the white of an egg mixed with lime. The surfaces of the grooves
may with advantage have copper deposited thereon before use, the block f takes up
any mechanical strain to which otherwise the burner would be exposed.
The burner having been placed in the globe I next proceed to form a vacuum
therein. Heretofore such exhaustion has been produced by means of a Sprengel
pump, which is a long, laborious, and at best incomplete method; I on the contrary
turn the globe or bulb upside down, pour mercury therein, and then by reversing
the position of the bulb I allow the mercury to escape, leaving behind a perfect
"Torricellian" vacuum and seal up the lower tubular extremity of the bulb by
The bulb is fitted to a tube not less
means of the blow-pipe in the usual manner.
than thirty one inches in length to overcome the pressure of the atmosphere. This
method of exhausting is also applicable to all other lamps requiring a vacuum to be
formed in the bulb or globe.
At Figure 6 I have shown an improved apparatus for accomplishing the object
in view substantially according to the same method. The bulb i for the incan-
descent burner a is formed with a tubej at the top, having a very narrow neck
at one point j¹, and a tube k at the bottom, having also a very narrow neck at k¹,
and the wires c, c, are sealed into the bottom of the bulb. To the bottom tube k
I connect an iron (or glass) tube m by means of a piece of flexible tubing and
The
thin wire. Over the tube m I pass a mercury cup n with a cork bottom o.
mercury in this cup serves to make a perfectly tight joint between the tubes k
and m
To this latter I also connect a
m¹ is a stop washer on the tube m.
flexible tube p which carries a mercury containing closed vessel q. The part of
the tube m below the stop m¹ is at least 28 inches long, that is, the minimum height
of a mercury column supported by the pressure of the atmosphere.
The mode of exhausting the bulb i is as follows:-The mercury vessel q is in the
first instance placed so that its mercury level is about as the level of the stop m¹.
While it is in this position the joint between the tubes k and m is made, and the
mercury cup n is then raised to the position shown on the Drawing. I then raise
the mercury vessel g to the position shown, that is, so that its mercury level is
even with the top of the tube j. The mercury in the vessel 9 and in the pipes p
and m will now rise up into the pipe k, and very slowly pass through the narrow
neck, thence slowly rise into the bulb i, and slowly pass through the neck j;
during all this time all the air will be displaced by the mercury and driven out at
the top of the tube j. The action is by means of the narrow neck ke rendered very
slow in order to prevent as much as possible the formation of any film of air

page_text: adhering to the interior sides of the passages thus traversed by the mercury, and
also in order to prevent injury to the burner a. But a very thin film of air will
nevertheless adhere to these interior parts; and in order to get rid of this air and
of the air contained in the pores of the burner I next proceed as follows:-I plug
the aperture of the tube j and seal it with moist putty, or otherwise close up
this aperture; I then lower the mercury vessel q until the mercury in the bulb i
descends below the narrow neck k¹. By this means the aforesaid thin air film in
the interior parts and also the greater portion of the occluded air in the burner is
liberated and collects in the bulb i and pipe j. I further now expel the remainder
of the occluded air or gas in the burner by passing a current through it. The
mercury vessel q is now raised to the position shown in the Drawing. The mercury
in q will then again slowly rise into the bulb i and tube j, driving the air right up
against the closed end of the tube j; the aperture of this tube is now opened to let
out this air and is then closed again. I then lower the vessel 9 so that the
mercury descends just below the neck, which then is sealed by means of the
blow-pipe. The vessel q is then further lowered so that the mercury descends
below the narrow neck k', which latter is then sealed by means of the blow-
pipe.
And having thus described and ascertained the nature of this Invention, and the
manner of carrying same into effect, I declare that I do not broadly claim
all the means herein specified for filling up the pores of the filament, but I
clain,
First. In the process of preparing or manufacturing incandescent electrical
burners, impregnating the fibre with boiled linseed or other drying oil, with or
without admixture of lamp black, and drying it previously to carbonizing for the
purpose of cementing the parts of the fibre together and imparting a smooth
surface to the filament by filling up the pores, substantially as described.
Second. In the process of manufacturing incandescent electrical burners
steeping the carbonized filament in boiled linseed or other drying oil, leaving it to
dry and then calcining for the purpose of filling up the pores, substantially as
described.
Third. In the process of manufacturing incandescent electrical burners, the mode
and means of connecting the conductor wires with the burner consisting in uniting
them by means of a carbonaceous cement, such as described, and then calcining
the cement, substantially as described.
Fourth. The mode of connecting the burner to the wires by means of a block
which relieves the burner of mechanical strain, substantially as described with
reference to Figures 4 and 5.
Fifth. The mode of forming the vacuum in a bulb for an incandescent lamp
consisting in expelling the air from the bulb by means of a column of mercury
forced into the bulb, all substantially as described.
Sixth. The combination of parts forming the apparatus for exhausting the bulb
of an incandescent lamp, substantially as described with reference to Figure 6.
In witness whereof, I, the said George Guillaume André, have hereunto set
my hand and seal, this Twenty-fourth day of April, in the year of our Lord
One thousand eight hundred and eighty two.