IMPROVEMENTS IN AND RELATING TO MEANS AND APPARATUS FOR ELECTRIC LIGHTING, PART OF SUCH IMPROVEMENTS BEING APPLICABLE ALSO TO OTHER PURPOSES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Desmond Gerald Fitz-Gerald at the
Office of the Commissioners of Patents on the 16th December 1880.
<
DESMOND GERALD Fitz-Gerald, of Brixton, in the County of Surrey, Electrician.
IMPROVEMENTS IN AND RELATING TO MEANS AND APPARATUS FOR ELECTRIC
LIGHTING, PART OF SUCH IMPROVEMENTS BEING APPLICABLE ALSO TO OTHER
PURPOSES."
This Invention relates to improvements in and relating to means and apparatus
for electric lighting, part of such improvements being applicable also to other
purposes.
According to my Invention I obtain the electric light by the incandescence of
carbonaceous or metallic conductors, traversed by the electric current.
When a carbonaceous conductor is employed, and more particularly when this is
obtained by the carbonisation of vegetable substance, I give to the conductor any
required degree of hardness or solidity and of electrical conductivity or resistance,
by treating the vegetable substance or the carbon obtained therefrom with
solutions rich in carbon (this element being liberated by subsequent ignition), also
with salts of the refractory metals, such as platinum or irridium, and with salts,
such as those of magnesium and cadmium, which when decomposed furnish an
infusible earth or oxide, the metal, earth or oxide being obtained in admixture with
the carbon.
I prefer to manufacture the carbonaceous conductor by carbonising natural
unwrought vegetable fibres, such as cocoa-nut fibre or whisk, piassava raffia, and
esparto or china grass. Such fibres and the resulting carbon may be treated as
aforesaid and as described below.
In order to facilitate the making of a perfect contact with the carbon conductor,
I coat its terminals with any suitable metal by means of electro-deposition or
otherwise, and I sometimes extend the coating of refractory metal to the whole
surface of the conductor. I prefer to enclose the conductor in a glass vessel filled.
with acetylene, cyanogen, olefiant, gas, or vapour of mineral naptha, and in certain
cases I enclose within the vessel a small quantity of potassium or sodium or of
compounds containing them with a view to the absorption of certain gases,
particularly oxygen, which may be accidentally present. Sometimes I maintain
the plenum of suitable gases by the passage of a continuous stream thereof through
the vessel containing the incandescent carbonaceous conductor.

page_text: When a metallic conductor is employed for producing the light, I embed it in an
infusible substance, such as magnesia or oxide of cadmium, in such manner as to
allow of the metal being raised to the temperature at which it softens or fuses. Or
I bring the two extremities of the metallic conductor into contact with two
conducting masses which are separated or insulated from each other by means of
an infusible earth or oxide, the metallic conductor which is to convey the current
being preferably placed in a groove or recess extending from one to the other of
the conducting masses across the fusible partition. This apparatus constituting a
kind of electrical crucible, is also applicable to purposes other than the production
of the electric light.