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On some early forms of electric furnaces
June, 1888.]
t~arly Forms oJ Electric Furnaces.
475
O~ SOME E A R L Y F O R M S oJ~ E I . E C T R I C F U R N A C E S . No. 7.
S I E M E N S ' E L E C T R I C F U R N A C E OR C R U C I B L E .
BY PROF. EDWIN J. HOUSTON.
In 1879, Charles William Siemens took out letters-patent in Great Britain for " I m p r o v e d Means and Apparatus for Producing Light and H e a t by Electricity." This patent is numbered 2I IO of t879. The completed specification is dated N o v e m b e r 26, I879. The matter contained in this patent, is, to some extent, an application of the principle described in a prior patent, No. 4208 of I878, to the same inventor. This principle consists briefly, in cooling one of the electrodes of an electric source, by means of a stream of water forced through a cavity in the same. Siemens applies this principle to the utilization of the direct heat of the voltaic arc for the heating of a crucible, in which furnace operations that require great heat may be conveniently carried on. The following general description of this process is taken from the provisional specification, viz : "In applying the electric current to the production of intense heat for the fusion of refractory substances, I employ two carbon rods, fitted to slide towards each other horizontally, within watereased tubes, which are attached to the opposite sides of a crucible made of highly refractory material, such as lime or alumina, also water-cased if necessary. The substance to be fused is introduced into the crucible, and the carbon rods are advanced sufficiently near to each other to form the voltaic arc within the crucible. T h e clockwork which advances them has a flyer which can be retarded or arrested by a brake or stop connected to a thin metal strip which forms a part of the electric circuit, or to the armature of an electro-magnet, the coil of which forms part of the circuit. As the heat in the crucible increases, the resistance to the voltaic arc within it diminishes, and consequently the arc can be elongated, a result which results from the automatic retardation or stoppage of the feeding clockwork. T h e crucible may be closed by a cover
476
ttomton
:
[ J. F. I.,
having apertures through which air or other gases may be blown or drawn to act on the substance under treatment. In some cases, instead of employing carbon for the terminals, they may, be m a d e of the material that is to be fused, when it has sufficient conductivity." It will be noticed that the electric furnace of Siemens does not differ, in its essential features, from the earlier forms described b y Depretz in connection with his experiments on the fusion of refractory substances, except that in some of Depretz's forms the voltaic arc did not play directly on the material subjected to fusion, but heated to intense incandescence the carbon crucible or vessel in
which said substance was placed. Depretz's furnace, however, provided no means for cooling the ends of the electrodes. Siemens' furnace was not merely a crucible in which the fusion of highly refractory substances was accomplished. The hollow carbons, or the perforated cover, provided for the introduction of air or other ~as, clearly shows that he contemplated the c a r , y i n g on of what might properly be classed as furnace operations, or reductions, under the influence of the high t e m p e r a t u r e o{' the voltaic arc. The forms of electric crucibles devised by Siemens will be best understood from tile fl)llowing description taken from tile corn-
June, 1888.]
.Ear/d, Forms o f HecZrz'c Fzlrlta<'es.
477
pleted specifications, viz: " ];z~. 4 shows apparatus according to my invention for applying the heat of the voltaic arc within a crucible." * * * " I have shewn in the F i g u r e one of the terminals A, to be a carbon, and the other B, as a metal pole cooled by circulation of water as described in the specification above referred to. Both terminals might, however, be carbons, and both
I
"J
I
~.,r either might be tubular, as shown w i t h respect to A, so t h a t currents of air or other gas might be sent t h r o u g h them into the crucible for effecting chemical reactions therein. T h e terminals rest on grooved rollers _/~, _R, being pressed down thereon by heavy rollers r, r." * * *~ * * * " W h e n the material treated in the crucible is a conductor, the arrangement shown in F @ . 5 , may be adopted. In this connection
478
HozlstoJl.
I J. t". I.,
material A, such as fused metal forming the one terminal, lies in the b o t t o m of tile crucible in contact with a screw or pin, (<, faced with the platinum or other metal that \rill not bc acted on by the material A. The other terminal ]~, which is cooled by the passage of water through it, as described in the specification above referred to, is suspended through a hole in the crucible cover, and it can I)e made to ascend or descend as required for regulating the distance between the terminals, by the action of a solenoid or expanding metal wire or strip as described above with reference to the carbons of electric lamps." In the operation of this crucible it was found that there was a tendency of the voltaic arc to pass to the walls of the crucible, rather than to the substance subjected to the heat. This tendency was, to a great extent, checked by surrounding the outside of the crucible with a coil of wire. Some experiments conducted with this crucible b y Dr. Siemens and Prof. Huntington, are recorded in a p a p e r read by them at the fifty-second meeting of the British Association for the Advancem e n t of Science, held in August, I882. The following abstract of some of the more interesting of these e x p e r i m e n t s is here given. The current employed, which was of from 25o to 30o amp6res, was obtained from five dynamo-electric machines, four of which were coupled together, aud the other was employed as an exciter. A number of difficult fusions were effi~cted, viz : (I) Six pounds of wrought iron were kept in the heat of thearc for twenty minutes and then poured into a mould. The cooled: metal was found to be crystalline and to no lm~ger possess the ability to be wrought. (2) T w e n t y pounds of steel were completely melted in one hour in a single charge. (3) Three-fourths of a pound of copper, placed in carbon dust, were melted in half an h o u r - - o n l y three-fourths of an ounce, however, was found remaining in the retort. T h e rest had been vaporized ! (4) One-quarter of an hour was sufficient to reduce eight pounds of platinum to the liquid state. (5) S o m e curious results are noticed b o t h during the fusion and vaporization of tungsten, and in the properties of the product as found in the electric crucible.
June,
Iqc~8.~
C/lloyo~]lj/l Plates, etc.
479
The electric crucible, as constructed by Dr. Siemens, must be regarded as admirably suited for investigation on the fusion of retractory sL~bstances. CI.;NTIC\L J:[IGI! ~CIIOOL,
PuI LADFLPUIa, ATf;'//.y, zS$S.
C H L O R O P H Y L AN,} G E L A T I N E - B R O M I D E
PLATES.
]~V FP, EI), E, IRES.
ERead al /he Staled J~,etila#, Wed*lesdav, Al~ril r$, x8gS.~ The isochromatic processes now most used are incapable of producing correct monochrome photographs of objects in all colors; eosine and erythrosine plates are insensitive to red, and even cyanine plates will not show any difference between a black and a deep red without greatly over-exposing orange and yellow. The original process gcollodion emulsion with chlorophyl) is the only one yet published which has not this defect. But most photographers do not like to use this process, because suitable chlorephyl caunot be procured at all times, nor preserved without considerable loss of sensitiveness, and the plates must be prepared immediately before use, and exposed wet, in a strong light. Many who have seen the beautiful results obtained with this process have lamented the fact that chlorophyl could not be applied successfully in the gelatine plate process, and I tried many times to accomplish it. On several occasions, I obtained considerable color-sensitiveness, but the result was so uncertain as to be puzzling and discouraging. A t last, however, I have succeeded in securing, by a surprisingly simple procedure, the full action of chlorophyl upon commercial gelatine-bromide plates. The degree of color-sensitiveness obtained appears to bear a definite relation to the general sensitiveness of the plate employed, which should, therefore, be of the most rapid kind. They are prepared by flowing with the alcoholic solution of chlorophyl, l/zeJz dr~blK rapidly, t/zelz soa/ei~z~ i,a zvater for at least five minutes, after which they may be used at once. Wit'h two-year-old chlorophyl (obtained from suitable leaves, at the proper st:ason, and
t~arly Forms oJ Electric Furnaces.
475
O~ SOME E A R L Y F O R M S oJ~ E I . E C T R I C F U R N A C E S . No. 7.
S I E M E N S ' E L E C T R I C F U R N A C E OR C R U C I B L E .
BY PROF. EDWIN J. HOUSTON.
In 1879, Charles William Siemens took out letters-patent in Great Britain for " I m p r o v e d Means and Apparatus for Producing Light and H e a t by Electricity." This patent is numbered 2I IO of t879. The completed specification is dated N o v e m b e r 26, I879. The matter contained in this patent, is, to some extent, an application of the principle described in a prior patent, No. 4208 of I878, to the same inventor. This principle consists briefly, in cooling one of the electrodes of an electric source, by means of a stream of water forced through a cavity in the same. Siemens applies this principle to the utilization of the direct heat of the voltaic arc for the heating of a crucible, in which furnace operations that require great heat may be conveniently carried on. The following general description of this process is taken from the provisional specification, viz : "In applying the electric current to the production of intense heat for the fusion of refractory substances, I employ two carbon rods, fitted to slide towards each other horizontally, within watereased tubes, which are attached to the opposite sides of a crucible made of highly refractory material, such as lime or alumina, also water-cased if necessary. The substance to be fused is introduced into the crucible, and the carbon rods are advanced sufficiently near to each other to form the voltaic arc within the crucible. T h e clockwork which advances them has a flyer which can be retarded or arrested by a brake or stop connected to a thin metal strip which forms a part of the electric circuit, or to the armature of an electro-magnet, the coil of which forms part of the circuit. As the heat in the crucible increases, the resistance to the voltaic arc within it diminishes, and consequently the arc can be elongated, a result which results from the automatic retardation or stoppage of the feeding clockwork. T h e crucible may be closed by a cover
476
ttomton
:
[ J. F. I.,
having apertures through which air or other gases may be blown or drawn to act on the substance under treatment. In some cases, instead of employing carbon for the terminals, they may, be m a d e of the material that is to be fused, when it has sufficient conductivity." It will be noticed that the electric furnace of Siemens does not differ, in its essential features, from the earlier forms described b y Depretz in connection with his experiments on the fusion of refractory substances, except that in some of Depretz's forms the voltaic arc did not play directly on the material subjected to fusion, but heated to intense incandescence the carbon crucible or vessel in
which said substance was placed. Depretz's furnace, however, provided no means for cooling the ends of the electrodes. Siemens' furnace was not merely a crucible in which the fusion of highly refractory substances was accomplished. The hollow carbons, or the perforated cover, provided for the introduction of air or other ~as, clearly shows that he contemplated the c a r , y i n g on of what might properly be classed as furnace operations, or reductions, under the influence of the high t e m p e r a t u r e o{' the voltaic arc. The forms of electric crucibles devised by Siemens will be best understood from tile fl)llowing description taken from tile corn-
June, 1888.]
.Ear/d, Forms o f HecZrz'c Fzlrlta<'es.
477
pleted specifications, viz: " ];z~. 4 shows apparatus according to my invention for applying the heat of the voltaic arc within a crucible." * * * " I have shewn in the F i g u r e one of the terminals A, to be a carbon, and the other B, as a metal pole cooled by circulation of water as described in the specification above referred to. Both terminals might, however, be carbons, and both
I
"J
I
~.,r either might be tubular, as shown w i t h respect to A, so t h a t currents of air or other gas might be sent t h r o u g h them into the crucible for effecting chemical reactions therein. T h e terminals rest on grooved rollers _/~, _R, being pressed down thereon by heavy rollers r, r." * * *~ * * * " W h e n the material treated in the crucible is a conductor, the arrangement shown in F @ . 5 , may be adopted. In this connection
478
HozlstoJl.
I J. t". I.,
material A, such as fused metal forming the one terminal, lies in the b o t t o m of tile crucible in contact with a screw or pin, (<, faced with the platinum or other metal that \rill not bc acted on by the material A. The other terminal ]~, which is cooled by the passage of water through it, as described in the specification above referred to, is suspended through a hole in the crucible cover, and it can I)e made to ascend or descend as required for regulating the distance between the terminals, by the action of a solenoid or expanding metal wire or strip as described above with reference to the carbons of electric lamps." In the operation of this crucible it was found that there was a tendency of the voltaic arc to pass to the walls of the crucible, rather than to the substance subjected to the heat. This tendency was, to a great extent, checked by surrounding the outside of the crucible with a coil of wire. Some experiments conducted with this crucible b y Dr. Siemens and Prof. Huntington, are recorded in a p a p e r read by them at the fifty-second meeting of the British Association for the Advancem e n t of Science, held in August, I882. The following abstract of some of the more interesting of these e x p e r i m e n t s is here given. The current employed, which was of from 25o to 30o amp6res, was obtained from five dynamo-electric machines, four of which were coupled together, aud the other was employed as an exciter. A number of difficult fusions were effi~cted, viz : (I) Six pounds of wrought iron were kept in the heat of thearc for twenty minutes and then poured into a mould. The cooled: metal was found to be crystalline and to no lm~ger possess the ability to be wrought. (2) T w e n t y pounds of steel were completely melted in one hour in a single charge. (3) Three-fourths of a pound of copper, placed in carbon dust, were melted in half an h o u r - - o n l y three-fourths of an ounce, however, was found remaining in the retort. T h e rest had been vaporized ! (4) One-quarter of an hour was sufficient to reduce eight pounds of platinum to the liquid state. (5) S o m e curious results are noticed b o t h during the fusion and vaporization of tungsten, and in the properties of the product as found in the electric crucible.
June,
Iqc~8.~
C/lloyo~]lj/l Plates, etc.
479
The electric crucible, as constructed by Dr. Siemens, must be regarded as admirably suited for investigation on the fusion of retractory sL~bstances. CI.;NTIC\L J:[IGI! ~CIIOOL,
PuI LADFLPUIa, ATf;'//.y, zS$S.
C H L O R O P H Y L AN,} G E L A T I N E - B R O M I D E
PLATES.
]~V FP, EI), E, IRES.
ERead al /he Staled J~,etila#, Wed*lesdav, Al~ril r$, x8gS.~ The isochromatic processes now most used are incapable of producing correct monochrome photographs of objects in all colors; eosine and erythrosine plates are insensitive to red, and even cyanine plates will not show any difference between a black and a deep red without greatly over-exposing orange and yellow. The original process gcollodion emulsion with chlorophyl) is the only one yet published which has not this defect. But most photographers do not like to use this process, because suitable chlorephyl caunot be procured at all times, nor preserved without considerable loss of sensitiveness, and the plates must be prepared immediately before use, and exposed wet, in a strong light. Many who have seen the beautiful results obtained with this process have lamented the fact that chlorophyl could not be applied successfully in the gelatine plate process, and I tried many times to accomplish it. On several occasions, I obtained considerable color-sensitiveness, but the result was so uncertain as to be puzzling and discouraging. A t last, however, I have succeeded in securing, by a surprisingly simple procedure, the full action of chlorophyl upon commercial gelatine-bromide plates. The degree of color-sensitiveness obtained appears to bear a definite relation to the general sensitiveness of the plate employed, which should, therefore, be of the most rapid kind. They are prepared by flowing with the alcoholic solution of chlorophyl, l/zeJz dr~blK rapidly, t/zelz soa/ei~z~ i,a zvater for at least five minutes, after which they may be used at once. Wit'h two-year-old chlorophyl (obtained from suitable leaves, at the proper st:ason, and