Improvements in or relating to the Manufacture of Refractory Metallic Threads.
Year: 1896

page_text: Date of Application, 2nd June, 1996-Accepted, 2nd June, 1897
COMPLETE SPECIFICATION.
Improvements in or relating to the Manufacture of Refractory
Metallic Threads.
A communication from ERNEST OBERLE, of 27 Rue Rennquin, Paris, in the Republic
of France, Engineer.
I, MONROE LEE Ross, of 29 Cornhill, in the County of Middlesex, Electrician 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 the present invention is the formation of threads from refractory
metallic oxides to be used chiefly in incandescent lighting by gas or in incandescent
electric lamps. My invention consists in a process for the preparation of solutions
composed of metallic salts and organic bodies, which can be spun through capillary
holes, with or without the use of pressure, in the air or in a liquid and give after
spinning a homogeneous thread, in which the metallic part exceeds considerably the
organic part, with which it is incorporated the latter being destined to be destroyed
either by heat or chemically. If a thread thus obtained is used for the manufacture
of a mantle to be used as an incandescent body for gas, such mantle has the advantage,
as compared with thread obtained by the hitherto used spinning processes, that its
contraction is only a normal one, in no way disturbing the homogeneity of the salts.
The metallic salts used by me are salts, in which the quantity of metal or oxide is
far in excess of that of acids. Such are for instance salts of thorium. Hitherto only
the nitrate of thorium has been used, the decomposition of which takes place in
accordance with the following formula ;-

page_text: When the thread is to be formed under pressure (in the atmosphere), I prepare a
strony solution of 20% of nitro-cellulose.
I mix these solutions of nitro-cellulose with the solution of ThoCl₂.
The oxychloride of thorium is capable of being spun when there is 20% of nitro-
cellulose to 80% of ThOCl2.
The alcohol must exceed in quantity the ether in the homogeneous solution even
when the thread is manufactured under pressure because ether precipitates Tho, or
basic salt of thorium.
I draw attention to the fact that the oxychlorides have the property of making
a solution of nitro-cellulose more transparent and more easily spun; the threads
obtained are more flexible and, what is the chief point, the decomposition of threads is
perfectly regular. After this decomposition I obtain a thread consisting of Tho,
relatively speaking very strong and regular.
2. SPINNING.
The homogeneous solution having been prepared as described, I spin either the
weak solution without pressure by making said weak solution pass through glass
tubes with capillary openings; these capillary openings are immersed in water and
I draw the solution (through water) by means of a clockwork or other device
(the alcohol and ether get dissolved in water); the thread is dried in the open air.
When a strong solution with 20% of nitro-cellulose is used (the complete solution
consists approximately of 20% nitro-cellulose 80% ThOCl, and 0.75 of cerium
oxychloride, dissolved in ether and alcohol), the solution is made to pass under
pressure into the open air.
3. PREPARATION OF THE INCANDESCENT BODIES PROPER.
The threads manufactured as described consist of nitro-cellulose, which serves as
a preliminary "vehicle," and of salts, the oxides of which are to be utilised.
The vehicle and the acids are destroyed by heat either in a closed vessel or in the
open air at low temperature. The oxy-hydrates, which are not destroyed, preserve
completely the original form of the threads.
The oxyhydrates are destroyed by heat by a strong Bunsen burner and the oxides
calcine, their density increasing till a perfect stability is reached.
There remains only to apply the incandescent bodies prepared as described to a
suitable burner.
To ensure regularity of decomposition there are several ways;-either I take the
nitro-cellulose of small degree of nitrification in order not to have small partial
explosions, or else I increase the proportion of oxychloride relatively to the quantity
of nitro-cellulose or I combine the two conditions of regular burning according to the
industrial requirements to be fulfilled.
There are other means of decomposition for making the oxides free: denitration
by ammonium hydrosulphide or soaking all the compound body of threads in water
before the decomposition, whereby the disengaging of the nitric acid is rendered
very regular.
It is evident that thorium oxychloride can be replaced by other salts such for
instance as salt of silver, platinum, or copper, and the thread produced or the metals
made free as has been described can be prepared and used for electric incandescent
lamps, and for other purposes, in a similar manner.
Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to me by my foreign correspondent and in what manner the
same is to be performed, I declare that what I claim is ;-
1. The process for preparation of refractory threads for manufacture of incandescent
bodies for gas or incandescent electric lamps and I claim as a distinctive feature of
my invention the preparation of solutions of salts of thorium and cerium and of

page_text: organic bodies the salts of these metals being chiefly taken in the shape of oxy-
chlorides and the organic bodies in the shape of nitro-cellulose in order to increase
the degree of concentration of salts the nitro-cellulose serving only as a vehicle to
facilitate spinning.
2. In the production of threads such as described the employment of metallic oxides
mixed with organic vehicles and passed through capillary tubes.
3. The use of oxychlorides of metals in the preparation of artificial mineral threads.
4. The employment of threads such as described for the manufacture and pro-
duction of incandescent bodies or cores of bell, globe or other desired shape and
fixed or movable.
5. The employment of threads such as described whether as simple threads or
as fabric in combination with an electric current whereby the threads are rendered
incandescent.
BOULT & WADE,
Agents for the Applicant.