Processes for Manufacturing Incandescible Materials.
Year: 1897

page_text: Date of Application, 2nd Oct., 1897-Accepted, 4th Dec., 1897.
COMPLETE SPECIFICATION.
Processes for Manufacturing Incandescible Materials.
I, WILLIAM LAWRENCE VOELKER, 133, West Jersey Street, Elizabeth, New Jersey
State of New Jersey, United States of America, 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 :-
This invention relates to Improvements in Processes for Manufacturing Incan-
descible Materials, for use in making Mantles or hoods for incandescent gas lights.
The invention especially relates to a process for producing a very intimate union,
I have
in such an incandescible material, of the oxides of magnesium and calcium.
found that a material produced by the union of the oxides of magnesium and calcium
has a high incandescent power and great durability, and the present invention relates
to an improved process for the manufacture of such a material.
I have found that no mere mechanical method, such as grinding the oxides, will
produce a sufficiently intimate union even with the addition of fusion after the
grinding, and without the aid of chemical re-agents. My present process resorts to
the action of chemical re-agents as one step, whereby I find the molecules of the
oxides of the two minerals are finally brought together in a most intimate arrange-
inent and union.
Essentially the process consists in treating the oxides of calcium and magnesiumi
together with any suitable acid which will produce inagnesium and calcium salts that
can be afterward decomposed back to the oxides and then reducing such salts to the
oxides. The oxides are then heated together by intense heat, as the electric arc, in
a suitable furnace; the result being a most intimate and durable combination of the
two oxides.
I find that nitric, hydrochloric or sulphuric acid may be used to produce the salts,
and I prefer nitric acid, although I do not limit the process to the use of any
particular acid.
Assuming nitric acid is to be used, the process is operated as follows: I first take
equal parts by weight of the oxides of calcium and magnesium, and reduce them to
the finest practicable powder by grinding in porcelain mills or mortars. The lumps
of the oxides may be put in the mill and ground together, or they may be ground
separately and then intimately mixed and reground; the object being to produce the
most thorough intermixture of the powdered oxides practicable. The powdered and
mixed oxides are next dissolved in nitric acid to which a trace of chromic acid may
be added if it is desired to give a ruddy tinge to the light, and the solution is then
evaporated by heat to the point of decomposition. At this stage of the process the
oxides are converted into nitrates, and I find by experience that during this solution
The
and decomposition the minerals are brought into a very intimate union.
evaporation is continued until the solution is reduced to a waxlike consistency. The
inass is then transferred to a magnesium or calcium crucible, heated to a bright red
heat and kept at this temperature for some time. For small amounts of material the
heating should be continued for about one hour for every pound of the material.
Thus, for five pounds of material the heating should be continued for between four
and five hours. For larger amounts of materials the heating can be proportionally
somewhat shortened. During this step the nitrates are decomposed and reconverted

page_text: into oxides of magnesium and calcium, and during this step again the intimate
union of the oxides is promoted. Upon the completion of the decomposition the
mass, consisting of the combined oxides of magnesium and calcium, is transferred to
a crucible and heated to the point of fusion in a suitable furnace, such as an electrical
furnace. It is preferably kept in a molten condition for some little time, to facilitate
the still further intimate union of the oxides. The molten mass is then allowed to
cool forming a cake which can be ground up and treated in a suitable manner to
form a mass from which filaments can be made, or the molten material can be run
into moulds and cast into sticks, from which filaments can be drawn by heating the
ends of the sticks sufficiently to soften them, and drawing them out just as glass is
drawn or spun and these filaments can be spun together to form a thread which can
then be knit into hoods or mantles.
-
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The process herein before described for manufacturing incandescible materials,
consisting in reducing the oxides of magnesium and calcium to salts together then
decomposing 'the salts and reconverting them into the oxides, then fusing the
resultant mass and finally cooling to a solid state.
S. S. BROMHEAD,
Patent Agent, 171, Queen Victoria Street, London E.C.