Incandescence Electric Lamps.
Year: 1888

page_text: Date of Application, 2nd Jan., 1888
Complete Specification Left, 2nd Nov., 1883
Complete Specification Accepted, 31st Dec., 188,
Luminant of Incandescence Electric Lamps.
1, JAMES YATE JOHNSON, of 47 Lincolns Inn Fields in the County of Middlesex,
Gentleman, do hereby declare the nature of this Invention, which has been communi-
cated to me from abroad by Theodore Mace, of 182 Fulton Street, New York, in the
United States of America, Merchant, to be as follows:-
:-
This Invention relates to the manufacture of the incandescing portion or luminant
of incandescent electric lamps.
Most or all natural fibres contain, besides the constituents carbon, hydrogen, and
oxygen, a variety of what may be termed impurities which on the carbonization of
the fibres become mere ash, which is detrimental to the success of the final result.
It is preferred for the purposes of this Invention to take natural growths which in
nature exist in an approximately filamentary form, in suitable lengths and of or
nearly of the diameter required. These are first reduced when necessary to a uniform
diameter throughout, which may be effected by pulling through holes in.draw-piates.
They are then treated in a bath of hydrochloric acid, preferably chemically pure and
having a specific gravity of 1-09, for say from 20 to 30 minutes. The effect of this
bath is to dissolve out all the silica and other ash making impurities of the fibre.
The fibres are then washed well and dried.
The fibres are then subjected to the action of undiluted sulphuric acid. The
undiluted commercial acid answers well for this purpose and it should have a specific
gravity of from 15 to 17. For example if alumina is to be subsequently incor-
porated by the decomposition of salts of alumina a specific gravity of 162 is
suitable for the purpose. If a pure carbon filament be wanted the materials will
after washing and drying be baked at a suitable temperature. But if the aim be
to produce a filament having a greater or lesser proportion of metallic oxide (say
of alumina) incorporated therein after the treatment in the sulphuric acid bath, the
fibres are washed in clean water but are not permitted to dry. Whilst still moist
or damp they are soaked for several hours in a solution of aluminium salt, for

page_text: instance, aluminium chloride, or sulphate. The fibres are then made ready for
baking by winding on carbon blocks or otherwise, and they are then baked' or
carbonized in the usual way. If the aluminium salt used be hygrometric, it is
desirable to keep the soaked fibres moist and warm up to the time of carbonization,
in order to prevent the gathering of globules of water along their length.
The effect of the preliminary treatment with hydrochloric acid is to remove the
impurities from, and open up the structure of, the fibres and so render them more
susceptible to the action of the sulphuric acid. The sulphuric acid on account of
its great affinity for water (the acid being undiluted) withdraws a large amount of
water from the fibre and as a consequence, it places the fibre in a condition in which
it will with great facility absorb the solution of metallic salt in the final step.
The final baking or carbonizing at a high temperature has the effect of decom-
posing the aluminium or other metallic salt, leaving the oxide in the filament; but
no separate or broad claim is made here to the process of incorporation of metallie
oxides by the use of a solution which is decomposed by the application of heat.
Natural fibres, when treated in the manner hereinbefore described are generally of
a yellowish tinge, and are extremely strong elastic and hard and will stand much
rough usage and when baked or carbonized at a high temperature are very hard and
elastic and of great density, and are peculiarly well adapted for use as the incandescing
media of incandescence electric lamps.

page_text: Luminant of Incandescence Electric Lamps.
I, JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention which has been com-
municated to me from abroad by Theodore Mace late of 182 Fulton Street New York
in the United States of America Merchant and at present of 132 Nassau Street New
York aforesaid and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
This Invention relates to the manufacture of the incandescing portion or luminant
of incandescent electric lamps.
Most or all natural fibres contain, besides the constituents carbon, hydrogen and
oxygen, a variety of what may be termed impurities, which on the carbonization of
the fibres become mere ash, which is detrimental to the success of the final result. It
is preferred for the purposes of this Invention to take growths which in nature exist
in an approximately filamentary form, in suitable, lengths and of or nearly of the
diameter required. These are first reduced when necessary to a uniform diameter
throughout which may be effected by pulling through holes in draw plates or by any
other suitable process. They are then treated in a bath of hydrochloric acid, preferably
chemically pure, and having preferably a specific gravity of 114 for say from 20
to 30 minutes. The effect of this bath is to dissolve out all the silica and other ash
making impurities of the fibre. The fibres are then washed well in water and
dried.
The fibres are then subjected for a few minutes (the exact length of time depending
on the character of the fibre), to the action of strong sulphuric acid. The ordinary
undiluted commercial acid answers well for this purpose, and should have specific
gravity of from 17 to 18 according to the extent of the following steps to be taken
towards the incorporation of metallic oxides. For example if the other step be, the
incorporation of alumina by the decomposition of alumínic salts (which is preferred)
the specific gravity of the sulphuric acid is graduated with that view, and it has been
found by my correspondent that a specific gravity of 1-78 is the most suitable for the
purpose. If a pure carbon filament be wanted, the materials will after washing and
drying be baked at a suitable temperature. But if the aim be to produce a filament
having a greater or lesser proportion of metallic oxide (say of alumina) incorporated
therein after the treatment in the sulphuric acid bath, the fibres are washed in clean
water but are not permitted to dry. Whilst still moist or damp they are soaked for
several hours in a solution of a metallic salt preferably an aluminium salt, such as for
instance, aluminium chloride or sulphate. The fibres are then made ready for baking
by winding on carbon blocks or otherwise and they are then baked or carbonized
which may be done in the usual way. If the metallic salt used be hygrometic, it is
desirable to keep the fibres dry after soaking, by the aid of gentle heat up to the
time of carbonization, in order to prevent gathering of globules of water along their
length.

page_text: The effect of the preliminary treatment with hydrochloric acid is to remove the
impurities from and open up the structure of the fibres and. so render them more
susceptible to the action of the sulphuric acid. The sulphuric acid on account. of its
great affinity for water (the acid being undiluted) withdraws a large amount of water"
from the fibres and as a consequence it places the fibres in a condition in which they
will with great facility absorb the solution of metallic salt in the final step.
The final carbonizing or baking at a high temperature has the effect of decomposing
the aluminium or other metallic salt, leaving the oxide in the filament, but no separate
or broad claim is made here to the process of incorporation of metallic oxides by the
use of a solution which is decomposed by the application of heat.
Natural fibres when treated in the herein before described manner with strong
sulphuric acid, and by drying are generally of a yellowish tinge, and are extremely
strong, elastic and hard, and will, stand much rough usage and when carbonized or
baked at a high temperature are very hard and elastic and of great density, and are
peculiarly well adapted for use as the incandescing media of incandescence electric
lamps.
By natural fibres I mean those which have not been treated to any manipulation
further than reduction in size to obtain the filamentary form. The action of sulphuric
acid upon such fibres is not to be confounded with the action which it has on such
manufactured fibres as cotton, thread or paper. In the latter the well known parch-
mentizing effect is produced, that is the thread or paper when treated with a mixture
of two volumes of concentrated sulphuric acid, and one volume of water, and then
washed, is transformed into a substance resembling parchment in appearance and
having the same composition as cellulose. In the process the fibrous structure is
destroyed and the body becomes translucent and homogeneous in character. By my
treatment of the fibre in its natural or unwrought condition, the result is different,
because the material is different. Cotton and linen are themselves almost pure
cellulose, without liqueous or woody tissue, and consequently without the stiffness and
a certain inflexibility, which strongly characterize natural fibres in their normal state.
The internal fibrous character is not totally destroyed, and the elasticity is very greatly
increased.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that. what I
claim is.
1. The manufacture of the incandescing portion or luminant of incandescent electric
lamps consisting in submitting natural unwrought fibres to the action of strong
sulphuric acid, then washing the treated fibres and incorporating metallic salts therein
and finally baking them, substantially as hereinbefore described.
2. The manufacture of the incandescing portion or luminant of incandescing electric
lamps consisting in first submitting natural fibres to the action of hydrochloric acid,
then washing, next submitting said fibres to a bath of strong sulphuric acid, and then
washing and incorporating metallic salts, and finally baking substantially as herein-
before described.
3. As a new article of manufacture the incandescing media or filaments produced as
herein before described and claimed.
Date thisEN
Lac