Improvements relating to the Preparation or Treatment of Carbons for Electric Lamps or Lighting Apparatus.
Year: 1890

page_text: Date of Application, 17th Sept., 1890
Complete Specification Left, 23rd May, 1891-Accepted, 11th July, 1891
.
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messrs. LACOMBE & Co., of 33, Rue de Lorraine,
Levallois, Perret, near Paris, in the Republic of France, Manufacturers.]
Improvements relating to the Preparation or Treatment of Carbons
for Electric Lamps or Lighting Apparatus.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention to be as follows:-
This invention relates to the preparation or treatment of carbons for electric arc
lamps or lighting apparatus.
It is well known that, with the carbons usually employed in electric arc lamps,
there is, in addition to the desired combustion at the arc, an objectionable or
undesirable secondary or ancillary combustion of the carbons a short distance from
the arc, which greatly increases the rapidity of consumption of the carbons. In
order to obviate this defect, the carbons have, in some instances, been covered or
coated with copper.
Now according to the present invention, the aforesaid defect is obviated as
follows, eiz.The carbon is impregnated or saturated with or has incorporated in
it, either before or after the baking thereof, one or more substances which, during
the burning of the carbons, are, by the chemical reactions to which they are
subjected, formed into a protective coating on the carbon, or into a non-oxidizing
medium around the same; or one or more substances which fill the pores of the
carbon and thus prevent the entrance of air into the same, but which do not
necessitate the baking of the carbon a second time, like the tar, molasses or similar
substances heretofore used for filling up the pores and increasing the solidity and
compactness of the carbon. The aforesaid protective substances prevent or greatly
diminish the said secondary or ancillary combustion. The substances which I use
for the purpose of my invention distil, decompose or volatilize at a very high
temperature, and produce the desired effects previous to their volatilization.
Various substances can be used to produce the effects above mentioned. As an
example of the substances which I employ for the purpose, I will mention phosphoric
acid and phosphate of ammonia.
I sometimes purify the carbon, either before or after the baking thereof, to
prevent the combination of the protective substance with the impurities contained
in the carbon.
When the protective substance is added to the carbon before the baking thereof,
the baking must be effected at a lower temperature than that required to decompose
or volatilize the protective substance or to otherwise destroy or impair the
properties which adapt it for the purpose of this invention.
Dated this 17th day of September 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION. .
Improvements relating to the Preparation or Treatment of Carbons
for Electric Lamps or Lighting Apparatus.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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 :-

page_text: This invention relates to the preparation or treatment of carbons for electric arc
lamps or lighting apparatus.
It is well known that, with the carbons usually employed in electric arc lamps,
there is in addition to the combustion at the arc, an objectionable or undesirable
secondary or subordinate combustion of the carbons a short distance from the arc,
which greatly increases the rapidity of consumption of the said carbons. In order
to obviate this defect the carbons have, in some instances, been covered or coated
with copper.
Now according to the present invention, the aforesaid defect is obviated as
follows, viz. The carbons are, after baking, impregnated or saturated with one or
more substances which, during the consumption of the carbons, are, by the chemical
reactions to which they are subjected, formed into a protective coating or into a
non-oxidizing medium around the same, or the carbons are impregnated or saturated
with one or more substances which fill the pores of the carbons and thus prevent
the entrance of air into the same, but which do not necessitate the baking of the
carbons a second time, as do the tar, molasses or similar substances heretofore used
for filling up the pores and increasing the solidity and compactness of the carbon.
The aforesaid protective substances prevent or greatly diminish the said secondary
or subordinate combustion. The substances which I use for the purpose of my
invention distil, decompose or volatilize at a very high temperature, and produce
the desired effects previous to and during their volatilization.
The substances which I employ to produce the effects above mentioned are
phosphoric acid and phosphate of ammonia.
I prefer to apply the phosphate of ammonia or phosphoric acid by placing the
carbons in solutions of the said substances and allowing them to remain therein
until sufficiently saturated. When conducted under ordinary atmospheric pressure
the operation will last about 5 or 6 hours, but by conducting the operation in _a.
vacuum it may be completed in a few minutes. After saturation, the carbons do
not require re-baking but they are dried preferably at a low temperature. I may
use any of the three well known forms of phosphoric acid, namely the ortho, the
pyro, and the meta, but I prefer the last named. As an example of a proportion
which gives a good result I give the following viz.:-20 per cent. by weight of
phosphoric acid or phosphate of ammonia and 80 per cent. water. This proportion
however depends upon the quality of the carbon.
I sometimes purify the carbon either before or after the baking thereof, to
prevent the combination of the protective substance with the impurities contained
in the carbon. We effect the purification in any well known manner, that is to
say, we treat the carbon with a suitable acid capable of removing silicon, iron, or
other metallic impurities. For example we may use hydrochloric acid, nitric acid,
or hydrofluoric acid.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me by
my foreign correspondent, I declare that what I claim is :-
First. The preparation or treatment of carbons for electric arc lamps or lighting
apparatus by saturating or impregnating the same, after baking, with phosphoric
acid or with phosphate of ammonia, for the purpose specified.
Second. A carbon that has been treated with substances such as those herein
specified for the purpose set forth.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.