IMPROVE- MENTS IN AND CONNECTED WITH ELECTRIC LIGHTING AND INCANDESCENT LAMPS
Year: 1882

page_text: LETTERS PATENT to Philip Middleton Justice of 14 Southampton Buildings
in the County of Middlesex Patent Agent for an invention of "IMPROVE-
MENTS IN AND CONNECTED WITH ELECTRIC LIGHTING AND INCANDESCENT
LAMPS." A communication from abroad by Alessandro Cruto of Piossasco
in the Kingdom of Italy
PROVISIONAL SPECIFICATION left by the said Philip Middleton Justice
at the Office of the Commissioners of Patents on the 20th April 1882.
Philip MIDDLETON JUSTICE of 14 Southampton Buildings in the County of
Middlesex Patent Agent "IMPROVEMENTS IN AND CONNECTED WITH ELECTRIC
LIGHTING AND INCANDESCENT LAMPS a Communication from abroad by Alessandro
Cruto of Piossasco in the Kingdom of Italy
33
This invention relates to incandescent lamps and to the combination and
arrangement of parts by which these lamps may be advantageously manufactured
as also to the means employed for regulating the current. The invention consists
of the improvements and arrangement of parts hereinafter described and set forth
To obtain carbons for incandescent lamps, heavy carburets of hydrogen or chlorides
of carbon are brought in contact with bodies whose surface contains aluminous
silicates or alkalines which decompose at the same temperature as the carbon
compounds. The best results are obtained when the walls or metallic wires covered
with said silicates are arranged vertically or slightly inclined The apparatus for
obtaining the carbons in the shape of strips may be made of a porcelain tubo
glazed inside and passing vertically through a furnace so that it is only heated at
the centre The tube is closed by suitable stoppers to one of which is attached the
gas or vapour supply pipe The upper portion of the apparatus is made of metal
and is supplied with a glass window through which the operation can be watched
for the purpose of regulation The vapour or gas employed is preferably carburetted
hydrogen which in passing through the heated part of the tube is decomposed and
yields particles of carbon and lamp black which are deposited on the glazed walls
in an uniform layer The residuim which is protocarbureted hydrogen continues

page_text: to rise and is slowly conducted away through a small pipe attached near the top of
the tube Instead of being formed of porcelain the tube may be formed of any
suitable material into which small open tubes of suitable shape made of porcelain
may be slipped while the centre of the outer tube is surrounded by a muffle. The
strips may be obtained of any suitable shape either directly or by cutting from
larger strips or sheets To produce them direct of any desired shape, such shape
should be formed in the porcelain before it is glazed If formed in large sheets
upon a smooth and even surface they can be cut like sheet gold and then bent into
the U-shape or other required form and this is deemed the preferable method To
obtain carbons in the form of a wire, a fine metallic wire is used and this is covered
with a thin coating of silicate say silicate of potash into a saturated solution of
which the wire is dipped several times, the water of said solution may be caused
to evaporate by means of an electric current The coated wire is then introduced
into a glass or other suitable tube into which the carbon compounds are introduced
and by means of an electric current the wire is brought to the temperature at
which the carbon compounds are decomposed and in this manner the wire receives
-an.outer_coating of carbon similar to that of the plain carbon strips When using
---very-fine-metallic wire similar to the platinum wire-of-Wollaston_it_may_remain in
the coating of carbon without inconvenience
If the wire be of platinum as this metal combines with the alkaline silicates
care should be taken to separate the wire from the silicate by a heavy coating of
carburet which may be obtained by exposing the wire to carburetted hydrogen
-and-making-it-red-hot by means of an electric current The carbons whether in
the shape of wires or strips should have their extremities thickened by means of a
metallic deposit or by dipping then in a mixture of tar pitch or asphalte and
silicate of potash and decomposing it at a gradually increasing temperature When
the top is fitted to the globe in which the carbon strip or wire is placed the joint
is made hermetically tight by means of mercury which is fed into an annular
groove formed between the two parts The interior surface of said groove may be
coated with platinum if desired
The closing cover is made in one or two parts and is provided with an opening
through which the mercury may be fed to the annular groove The lower part of
the cover is supplied with two platinum wires connected by means of a screwed
sleeve to the wires in connection with the carbon to which they are secured by
clamps, or two small tubes fitted with conducting material may be employed The
wires or tubes to the carbon are held in position by means of a glass disc which
may be coated with metal or otherwise polished on one side so as to act as a
reflector and to prevent the loss of heat, the rays of which are thrown off to the
upper portion of the lamp To obtain a vacuum in the lamp the globe and cover
are placed in clamps which are secured by suitable screws and catches. The cover
is slightly lifted and a rubber or other packing ring inserted and liquid is poured
into an annular cup formed around the joint, the lamp being then attached to the
apparatus for producing a vacuum while the before referred to annular groove is
placed in connection with both the apparatus and the interior of the lamp When
the maximum vacuum has been obtained the cover is replaced in position and the
groove filled with mercury The lower part of the cap or cover may be provided
with a hole in connection with the groove and the upper part be made capable of
rotation and also provided with a hole through which when both holes correspond
the vacuum may be obtained, and the mercury supplied When the latter operation
has been completed the upper part of the cover may be turned so as to close the
opening in the lower part
The apparatus for producing the vacuum I arrange as follows
To the base of a spherical vessel of large capacity is secured the tube which runs
to and is connected, with one or more lamps in which the vacuum is to be produced
From the top of the first spherical vessel a small pipe of 2 to 3 / in interior
diameter leads to a second vessel and passes through its cork or top into its interior

page_text: To the lower portion of the first vessel is attached lead or glass tube of say 6 meters
in length which terminates in a moveable receptacle of wood or iron lined with
lead Through the top or cork of the second vessol a tubo passes which is in
connection with the pneumatic apparatus
Sulphuric acid is introduced into the receptacle below the first vessel and also
into the second vessel and the pneumatic, machine is put in operation until the
maximum vacuum has been obtained The receptacle beneath the first vessel is
raised and the sulphuric acid by the pressure of the atmosphere fills the first vessel
driving its contained air into the second vessel from which it is drawn by the
pneumatic machine until all is exhausted and the acid itself is carried over into
the second vessel at this point the receptacle is lowered and the acid is drawn
back by the force of gravitation and in passing by the extremity of the pipe leading
to the lamps it draws the air from them, and by several repetitions of this operation
an almost perfect vacuum will be obtained During the operation care must be
taken that only a small quantity of acid passes over into the second vessel. If
however an excess should accumulate the pressure in the second vessel should bo
allowed to increase until a portion of the acid is returned to the first vossel For
the automatic regulation of the current I have found it convenient to employ two
sealed vertical tubes of glass communicating at their lower parts In one is spirally
coiled a resistance coil the ends of which of courso pass through the tube said tube
contains mercury and a few drops of a volatile liquid such as alcohol, the other
tube contains a more volatile or expansive liquid such as ether. The expansion in
the second tube should be arranged so as to be equal to the sum of the maximum
expansion in the first tube at a fixed temperature plus the difference in the heighth
of the mercury in the two tubes
In interposing this regulator in an electric circuit if the current which runs
through the wire is not too strong it will heat the volatile liquid in the first tube
only to such a degree as will cause no change If on the other hand the current
becomes too strong and produces a heat beyond the fixed degree then the volatile
liquid will vapourize and press the mercury in the first tube down until it abandons
so much of the wire coil as is requisite to increase the circuit resistance
The second tube containing air and one or more volatile liquids it follows that
the pressure it brings to bear upon the regulator increases or decreases according to
the temperature, and in this manner the amount of resistance interposed in the
circuit is regulated In order that the regulator may act by a slight rise in the
temperature at the lamps a conical metallic wire is placed in the centre of the first
tube and is secured at its thickest end to the upper part of the resistance coil or
several wires of graduated length may be employed In this arrangement the inetal
which gives passage to the current is more and more reduced as the mercury falls
consequent upon a rise in the temperature and thus an elevation of temperature is
produced in the regulator without increase of incandescence in the lamps. There
are regulators in which the maximum degree of temperature may be varied at will
In certain cases the two tubes inay be united by a rubber pipe and so arranged
that the second tube may rise or fall relatively to the first Others may bo
arranged with mechanism by which the pressure in the second tube can be varied
at will In these various cases the resistance to be put in the circuit is not limited
to the coil contained in the tube but may be much greater The tube may
be provided with a series of spirals arranged so as to permit of any desired
resistance.
A regulator suitable to be placed in the centre of a group of lights may be
formed of a tube with its resistance coils placed in the mercury contained in a
second tube at its base When a very strong current is employed as in lighting
many lamps, thick wires should be used and these would be difficult to place in
glass tubes or receptacles In this case I employ what I term composite regulators
and in which the current passing through tho tube would only be derived from the
principal current to be regulated

page_text: In this form of regulator the tube carries external resistance coils or electro
magnets. The tube is filled with liquids and the current passes from the wire to a
moveable piece or key thence to a support and through further supports and keys
to the delivery wire. The supports are connected by means of a thick wire or
bar upon which slide clamps holding the wires and by the increase or decrease in
the distance the sensibility of the regulator is controlled The spiral of the tube
being interposed in the circuit, if the current be too strong the mercury in falling
compels the derived current to pass through the electro magnet which attracts the
moveable piece or key and compels the principal current to pass through one or
more resistance coils and in this manner the current supplied to the lamps is
regulated

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Philip Middleton Justice in the Great Seal Patent Office on the
17th October 1882.
PHILIP MIDDLETON JUSTICE of 14 Southampton Buildings in the County of
Middlesex Patent Agent IMPROVEMENTS IN AND CONNECTED WITH ELECTRIC
LIGHTING AND INCANDESCENT LAMPS-A communication from abroad by Alessandro
Cruto of Piossasco in the Kingdom of Italy
This Invention relates to incandescent lamps and to the combination and
arrangement of parts by which these lamps may be advantageously manufactured
as also to the means employed for regulating the current The invention consists
of the improvements and arrangement of parts hereinafter described and set forth
To obtain the carbons for incandescent lamps I proceed as follows I bring heavy
carburets of hydrogen or chlorides of carbon in contact with substances, at the
temperature of decomposition, of the said components of carbon It will be noted
that the best results are obtained when the walls or metallic threads which may or
may not be covered with aluminous silicates, are placed vertically or only slightly
inclined. The best arrangement of apparatus known to me for obtaining carbons
in the form of thin sheets or strips is that represented in Fig I of the accompanying
drawings
A tube "A" of porcelain with glazed interior surface, passes vertically through
a furnace in such a manner that it will only be heated in its central part. To the
extremity of the tube A which is closed by a button or stopper of caoutchouc or
of cork is attached a pipe to conduct the gas or vapour to the tube The upper
part of the apparatus is of metal, and is united to the porcelain tube by means of
a caoutchouc band or tube A glass window in the upper part permits the
operation in the tube to be watched and regulated The vapour or gas which I
prefer to employ is carburetted hydrogen which in traversing that portion of the
tube which is heated to the requisite degree for its decomposition will yield in
part carbon in flakes which will be deposited on the glazed walls, and also in part
lamp black The residual gas which is proto carburet of hydrogen continues to rise
and is slowly conducted away through the small pipod Amongst the number of
other methods which may be employed, the following may be mentioned. A
tube B Fig 2 of any suitable material which will resist the requisite temperature
is vertically placed in a furnace within a muffle of refractory material Sliding
easily in the tube are open circular or polygonal cylinders of porcelain b, b', b³, b³
The sheets can be obtained of the desired form and dimensions either by direct
production or by cutting from larger sheets For direct production of any given
size, the design should be traced or formed on the porcelain before it is glazed
The best system appears to be however to employ tubes which present a plain and
polished surface, and to that end they should if of circular form be turned before
glazing, and if of polygonal or other section, they should be made with a smooth
surface. In this manner sheets may be obtained of comparatively large size which
As the sheets are
can be cut to the desired size and shape like sheet gold
flexible it is preferable to make them straight, and bend them subsequently into u
U form when they are to be placed in a lamp To obtain carbons in the form of
a thread I take a fine meta wire such as platinum formed into the desired shape
and held by small vices or clamps applied to a small piece of cork and place it in
a glass tube through or in which is made to pass a composition of carbon, in the
form of gas or vapour such as carburetted nydrogen If the wire be then made

page_text: red or white hot by means of an electric current, carbon will be deposited upon it
of the same quality as that obtained in the sheets At the commencement, the
temperature of the wire should be such as will decompose the components of
carbon without melting the wire This operation will take from 20 to 50 minutes
To ensure the carbon having an equal and uniform electrical resistance throughout
its entire length, the wire should be turned slowly during the operation of
decomposition. The second operation consists in the volatilization of the wire
For this it is first necessary to cut a little from the ends of the carbons, to uncover
the wire and then replace them in the vices or clamps I then close the apparatus
and again admit the same kind of gas or vapour If I desire increasing the size of
the carbon. If not I admit any other kind of gas, provided it will not attack the
carbon; a very good mixture for this purpose is ths Hydrogen and 1/10th car
buretted hydrogen This done the intensity of the electric current is slowly
brought up to the requisite temperature for the volatilization of the wire.
After bringing up the carbon to the "resistance type" carburetted hydrogen is
again admitted and an electric current of given intensity passes through the
carbon By this process the carbons can be made singly or in quantities
The manner of attaching the carbon strip or thread to the platinum thread is as
follows. The ends of the carbons are first enlarged by electrotyping-with-copper
then with a clamp or vice communicating with the positive pole of a 15 or-20-cell
Bunsen battery (or any other electric source) I tako separately the metallic
wires which have been already soldered in the glass, and with another clamp or
vice I take the enlarged end of the carbons, the circuit being open, it is placed in
the desired position in contact with-the-platinum wire If the circuit be then
closed, and the clamp holding the carbon, be placed in communication with the
negative pole of the battery the two extremities become heated. and soldered to
each other.
To complete the operation the platina wires soldered in the glass, and the
enlarged ends of the carbons are plunged into a galvanic bath to cover them
with a new coating of copper and give them an uniform colour as well as
to enlarge the metallic parts and give them a greater electrical resistanco
The carbons thus prepared may be placed in sealed globes of the ordinary kind, or
globes provided with grooved tops filled with mercury to forin an hermetical sealing,
may be employed The apparatus for producing the vacuum 1 arrange as follows
reference being made to Figure 3 of the drawings. To the base of a spherical
vessel C of large capacity is secured the tube E. which runs to and is connected
with one or more lamps in which the vacuum is to be produced From the top of
the spherical vessel C a small pipe c of 2 to 3 m/m in interior diameter leads to a
second vessel E and passes through its cork or top into its interior To the lower
portion of the vessel O is attached a lead or glass tube "a" of say 6 meters
in length which terminates in a moveable receptacle D of wood or iron lined with
lead
Through the top or cork of the vessel E a tube x passes which is in connection
with the pneumatic apparatus Sulphuric acid is introduced into the receptacle D
below the vessel C and also into the vessel E and the pneumatic machine is put in
operation until the maximum vacuum has been obtained The receptacle D beneath
the vessel C is raised and the sulphuric acid by the pressure of the atmosphere fills
the vessel C driving its contained air into the vessel E from which it is drawn
by the pneumatic machine until all is exhausted and the acid itself is carried
over into the vessel E At this point the receptacle D is lowered and the acid is
drawn back by the force of gravitation and in passing by the extremity of the
pipe E leading to the lamps it draws the air from them, and, by several repetitions
of this operation an almost perfect vacuum will be obtained During the operation
care must be taken that only a small quantity of acid passes over into the vessel E.
If however an excess should accumulate, the pressure in the vessel E should be
allowed to increase until a portion of the acid is returned to the first vessel C
For the automatic regulation of the current I have found it convenient to employ

page_text: two sealed vertical glass tubes F and G Fig 4 communicating at their lower parts.
In F is spirally coiled a resistance coil, the ends of which of course pass through
the tube, said tube contains mercury and a few drops of a volatile liquid such as
alcohol, the tube G contains a more volatile or expansive liquid such as ether. Tho
expansion in the tube G should be arranged so as to be equal to the sum of the
maximum expansion in the tube F at a fixed temperature plus the difference in the
heighth of the mercury in the two tubes In interposing this regulator in an
electric circuit, if the current which runs through the wire is not too strong, it will
heat the volatile liquid in the tube F only to such a degree as will cause no change
If on the other hand the current become too strong and produces a heat beyond the
fixed degree, then the volatile liquid will vapourize and press the mercury in the
tube F down until it abandons so much of the wire coil as is requisite to increaso
the circuit resistance The tube G containing air and one or more volatile liquids
it follows that the pressure it brings to bear upon the regulator increases or.
decreases according to the temperature, and in this manner the amount of resistance
interposed in the circuit is regulated In order that the regulator may act by a slight
rise in the temperature at the lamps, a conical metallic wire is placed in the centre
of the tubo F and is secured at its thickest end to the upper part of the resistance
coil, or several wires of graduated length may be employed In this arrangement
tho metal which gives passage to the current is more and more reduced, as tho
mercury falls consequent upon a rise in the temperature and thus an elevation of
temperature is produced in the regulator without increase of incandescence in the
lamps There are regulators in which the maximum degree of temperature may be
varied at will In certain cases the two tubes may be united by a rubber pipe and
so arranged that the second tube may rise or fall relatively to the first Others may
be arranged with mechanism by which the pressure in the tube G can be varied
at will In these various cases the resistanco to be put in the circuit is not
limited to the coil contained in the tube, but may be much greater Figure 5
represents a tube with its spiral arranged so as to interpose any desired resistanco
Figure 7 represents a regulator of a convenient shape for many cases, and especially
for placing in the middle of a group of lights Tube L and the spirals are soldered,
and plunged in the mercury of tube M The sealing may be done by a rubber
cork, or a glass stopper ground with emery When a very strong current is
employed as in lighting many lamps thick wires should be used and these would
be difficult to place in glass tubes or receptacles In this case I employ what I
term composite regulators as shown in Fig 6 and in which the current passing
through the tube would only be derived from the principal current to be regulated
In this form of regulator the tube H carries external resistance coils or electro
magnets The tube is filled with liquids and the current passes from the
wire fto a moveable piece or key thence to a support and through further
supports and keys ij to the delivery wire K The supports h and i are connected
by ineans of a thick wire or bar upon which slide clamps holding the wires and
by the increase or decrease in the distance the sensibility of the regulator is
controlled The spiral of the tube H being interposed in the circuit, if the current
be too strong the inercury in falling compels the derived current to pass through
the electro magnet which attracts the moveable piece or key j and compels the
principal current to pass through one or more resistance coils P And in this
manner the current supplied to the lamps is regulated
Having now described the invention of my foreign correspondent and how the
same may be practically employed What I claim and desire to secure by Letters
Patent is
1st The improvement in the manufacture and preparation of carbon either in
thread, strip or sheet form, for subsequent use in electric lamps substantially
as hereinbefore described
2nd In the manufacture of electric lamps the method of and apparatus for
If the nuznocas set forth

page_text: 3rd The improved method of and apparatus for regulating the electric current
supplied to electric lamps and consequently the amount of incandescence
all substantially as and for the purposes set forth.
In Witness whereof I the said Philip Middleton Justice have hereunto set
my hand and seal this sixteenth day of October in the year of Our
Lord one thousand eight hundred and eighty two
med, sealed and delivered
n the presence of
HENRY B HATCHWELL
Southampton Buildings
Chancery Lane
W.C.
PHILIP M. JUSTICE (L.S.)