US2119680A - Method and means for the manufacture of electrical resistances - Google Patents

Description

B. LONG June 7, 1938.

METHOD AND MEANS FOR THE MANUFACTURE OF ELECTRICAL RESISTANCES Filed June 14, 1935 4 Sheets-Sheet l INVENTOR. 552M420 L ONG MA? w w ATTORNEYS June 7, 1938. B. LONG 2,119,680

METHOD AND MEANS FOR THE MANUFACTURE OF ELECTRICAL RESISTANCES Filed June 14, 1935 4 Sheets-Sheet 2 INVENTOR. 352M420 A 0N6 ATTORNEYS B. LONG June 7, 1938.

METHOD AND MEANS FOR THE MANUFACTURE OF ELECTRICAL RESISTANCES Filed June 14, 1935 4 Sheets-Sheet 3 INVENTOR. BENAEO Z 0N6 BY fl/Z/wto w ATTORNEYS B. LONG June 7, 1938.

METHOD AND MEANS FOR THE MANUFACTURE OF ELECTRICAL RESISTANCES Filed June 14, 1935 4 Sheets-Sheet 4 INVENTOR. 355N420 L ONG ATTORNEYS Patented June 7, 1938 PATENT OFFICE METHOD AND MEANS FOR THE MANUFAC- TURE OF ELECTRICAL RESISTANCES Bernard Long, Paris, France, assignor to Societe Anonyme des Manufactures des Glaces &

Produits Chimiques de Saint-Gobain, Chauny & Cirey, Paris, France Application June 14, 1935, Serial No. 26,560 In France June 14, 1934 17 Claims.

This invention relates to an electrical resistance heater, and particularly relates to an electrical resistance heater in which the supporting structure is formed of a tempered glass and it also relates to methods of preparing such electrical resistance heaters.

In prior art, some of the electrical resistances were manufactured by a cathodic sputtering of metallic particles upon plates of ordinary nontempered glass. This method is very expensive and may be used only for the purpose of manufacturing articles of small dimensions. The coated surface of these articles is very fragile on account of its very small thickness and cannot resist higher temperatures.

An object of the present invention is the provision of a process for manufacturing electrical resistances which can be subjected to comparatively higher temperatures without being deteriorated and which are capable of resisting rapid changes of temperature.

Another object is the provision of electrical resistances manufactured by projecting metallic particles in the form of strips or bands upon surfaces of vitreous or vitrified bodies, which have a predetermined resistance and which are durable in operation and which may be utilized as heat resistors for domestic, factory or office use.

A further object is the provision of tubular resistances which are manufactured by projecting metallic particles upon supporting bodies having a curved or tubular form.

Yet anothgr object of the present invention is the adaptation of electrical resistances, manufactured by the projection of metal particles, for the purpose of supplying heat to surfaces of automobile wind-shields, windows and the like in order to prevent a deposition of moisture, snow 40 and frost upon these surfaces.

The above and other objects of the present invention may be realized by projecting metal in a molten and pulverized state in the form of a strip upon a vitrified surface or upon a support consisting of a vitreous insulated material. The resistance of the article manufactured by this method which depends upon the nature of the metal used and the conditions under which it was deposited upon the support, may be pre- 50 determined in advance.

When this method is applied to the manufacture of tubular resistances, particularly straight tubes. the sinuous strips formed by the projected metallic particles may be constituted by a series of metallic deposits which cover the tubes arranged side by side. These deposited metallic layers may be inter-connected alternately at one or the other end of the tubes by means of any suitable metallic connecting pieces.

The support for the metallic strips or bands may be made of tempered glass, said glass being capable of withstanding high temperatures and sudden variations of temperatures.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing by way of example preferred embodiments of the inventive idea.

In the drawings:

Figure 1 is a perspective view of a heating plate manufactured in accordance with the principles of the present invention.

Figure 2 shows in perspective an electrical radiator comprising a plurality of plates illustrated in Figure 1.

Figure 3 is a plan view of a heating device for domestic use consisting of a single heating plate.

Figure 4 is a section along the line 44 of Figure 3.

Figure 5 shows in elevation a radiator comprising a plurality of vertical tubes constructed in accordance with the principles of the present invention.

Figure 6 is a section along the line G--6 of Figure 5.

Figure 7 shows in perspective and on a larger scale the device used for holding one of the tubes shown in Figures 5 and 6.

Figure 8 is a horizontal section illustrating diagrammatically a radiator of a different form.

Figure 9 is a vertical section through another radiator comprising a plurality of horizontal tubes.

Figure 9a illustrates a tube provided with an inner metallic coating.

Figure 10 is a front view of a wind-shield provided with a heating element constructed in ac cordance with the present invention.

Figure 11 shows in front elevation a windshield of a different construction.

Figure 12 is a front view of a wind-shield provided with a movable sheet of glass.

Figure 13 is a section along the line |3|3 of Figure 1.2, and Figure 14 shows a differently heated wind-shield.

Fig. 15 is a section along the line |5l5 of Fig. 14.

A preferred method of manufacturing electrical resistances in accordance with the present invention, consists in projecting particles of finely divided molten aluminum upon a surface of tempered glass by means of a current of air or of one or more oxidizing gases.

The method of projecting metallic particles upon a glass surface which may be used to manufacture resistances constructed in accordance with the present invention, is described in the copending application of Bernard Long, Serial No. 733,454, filed July 2nd, 1934, relating to coated glass articles and a method of manufacturing the same.

According to the said co-pending application, Serial No. 733,454, the glass body on which the metal particles are projected is previously tempered by heating it to a temperature which is close to that at which the glass begins to get soft and by rapidly and suddenly cooling it to a low temperature and preferably a temperature between 200 C. and 400 C.

The temperature is varied for different types of glass and is lower than the temperatures at which stresses are likely to be developed within the cooled glass body.

The molten spray of finely divided aluminum is preferably projected upon this tempered glass surface while or after the tempered glass surface has been heated to a temperature of between 200 and 400 C., and the metal so applied to the glass surface will be found to adhere most closely to the glass surface and also to adhere together in spite of the fact that it is partly oxidized and therefore acquires a relatively high resistance to flow of electricity.

In accordance with the present invention, this method is further improved by regulating the relative proportions and amounts of the gaseous current and of the distance from which the metallic particles are projected upon the glass surface. By suitably regulating and varying such distances and also by varying the relative amounts of metal and gas, it is possible to vary the amount of oxidation of the metal. Since the specific resistance or the resistivity of a metallic element depends upon the degree or amount of oxidation of its metal, it follows that it is possible to manufacture articles having a predetermined electrical resistance by varying the distance'from which the metallic particles were projected and by varying the relative amounts of. the gas and of the metal.

The heating elements illustrated in Figures 1 and 2 of the drawings consist of glass plates I5 which may be made out of transparent or opaque glass. It is advisable to employ plates made of tempered glass as supports for the electrical resistances.

As shown more clearly in Figure 1, aluminum particles are projected upon two side surfaces of the glass plate I5 through a nozzle I6 along with a compressed oxidizing gas. It is advisable to deposit the aluminum particles upon the plate I5 in the form of a narrow strip I1 extending in sinuous-like curves from the top to the bottom of the plate, the end of each curve constituting the beginning of an adjacent curve. By varying the distance between the nozzle I6 and the plate l5, and/or by changing the composition of the gas transporting the metallic particles to the plate IS, the specific resistance of the metallic strip I! carried by the glass plate l5 can be determined in advance. The aluminum particles deposited upon two side surfaces of the plate I5 are oxidized to a greater or smaller extent depending upon the desired resistance of the heating element.

As shown in Figure 2, the plates I5 are carried by an insulated support I8 which is provided with terminals I9 and 20 made of a conducting material and adapted to be connected to any suitable source of electrical energy not shown in the drawings. The support I8 also carriestwo rows of metallic clamps 2| and 29. Each of these clamps comprises flanged portions 22 attached to the upper surface of the support I8. The clamps 2| and 29 are also provided with resilient hookshaped members 23 adapted to hold tightly the plates I5.

The lower ends of the plates I5 are situated within parallel grooves 24 formed in the support I8. The clamps 2| and 29 are placed above the grooves 24 so that the plates I5 may be conveniently held in place by these grooves.

In the modification illustrated in the drawings each of the plates I5 is carried by a clamp 29 and a clamp 2 I. The clamps 2| and 29 are arranged in two parallel rows on opposite sides of the support I8, the middle portion 25 of the support being hollow.

The clamps 2| and 29 transmit the electrical current supplied by the source of electrical energy to the terminals I9 and 20, to the strips I! carried by the plates I5. As shown in Figure 2, the first clamp 29a located near the terminal I9 is electrically connected by a contact piece 26 with the terminal, so that the electrical current flowing through the terminal I9 passes through the plate 26 and the clamp 29a.

The resilient bent portion 23a of the clamp 29a transmits the electrical current to the end strip I'Ia of the heating element. The electrical current will flow through the metallic layer across the entire plate until it reaches the clamp 2Ia. The current will flow from the resilient portion 23b of the clamp 2Ia through the U-shaped metallic portion 21 of the clamp 2|a or around a coatededge of the plate |5 to the second resilient member 230 which is situated on the opposite side of the plate I5. Since the plate I5 is coated on both sides by the metallic strips H, the current will flow across the back surface of. the heating element to the second resilient member of the clamp 29a.

The clamp 29a is connected with the adjacent clamp situated on the same side of the support I8 by a conducting member 28. Due to this arrangement, the electrical current leaving the first plate will be transmitted to the second plate.

In general, two resilient members 23 of each of the clamps 2| are electrically connected with each other. connection between the two resilient members of each of the clamps 29. Each of the clamps 29 is connected, however, with the adjacent clamp 29 by a metallic strip 28. Due to this arrangement, all the metallic strips I! carried by the plates l5 are inter-connected in series with each other, the last clamp 292 being electrically connected with the second terminal 20.

It is possible to group conducting strips ll of the same plate I5 or several plates carried by a support in a different manner. For instance, in the case of a three-phase alternating current, the plates or the strips carried by a single plate may be arranged in three groups in a delta or star connection.

The device, shown in Figures 3 and 4, may be used in the household for heating plates or the like. This device comprises-a plate 30 made of tempered glass which is carried by an annular support 3| and which is clamped to the support On the other hand, there is no electrical by themetallic flanges 32. The lower surface of theplate 30 carries a metallic strip 33 which is formed by projecting aluminum particles upon the glass surface in a sinuous-like curve. In the modification shown in the drawings, the two ends of the metallic strip or band 33 are situated close to each other and are connected with the conducting rods 34 and 35, respectively. Any suitable socket connected with a source of electrical energy having a voltage ordinarily employed for domestic consumption, may be connected with the rods 34 and 35. In the example illustrated, each of the rods 34 and 35passes through the support 3| and an insulated plate 36 attached to one of the side surfaces of the support 3|. Resilient blades 31 attached to an inner surface of the support 3| are used for connecting electrically the metallic layer 33 with the rods or terminals 34 and 35.

The annular support 3| is carried by the legs 33 and is connectedwith a handle 33 made of a heat insulating material. A plate 40 which is also made of a heat insulating material is attached to the lower surfaces of the support 3|. The purpose of the plate 40 is to prevent heat from escaping in a direction toward the bottom of the article and to direct the heat rays upwardly so that they may be used for the purpose of heating a plate or other object placed upon the upper surface of the glass plate 30.

Since tempered glass loses its hardness at a temperature which is over 400 C., the heating elements constructed in accordance with the present invention, should not develop any higher temperatures. This is conveniently accomplished in accordance with the present invention by providing heating units having a comparatively large heating surface so that the amount of heat per unit of area of the heat radiating surface is comparatively small. Furthermore, the heating plates manufactured in accordance with the present invention are decorative and ornamental in appearance. This artistic appearance may be further enhanced by suitably varying the form of the metallic layer or by applying the metallic layer in the form of any suitable ornamental design or drawing. The glass surfaces and the metallic surfaces may be polished if desired.

The radiator illustrated in Figures 5, 6 and '7 of the drawings comprises a plurality of glass tubes 50, the outer surfaces of which are covered by a metallic coating applied to these surfaces by projecting molten metallic particles thereon. The glass tubes 50 together with their supports form a cage-like structure provided with vertical bars.

The tubes or pipes 50 are carried at their upper and lower ends by supports 5| and 52, respectively. Each of these supports may have a rectangular form and is made of an insulating material. A vertical column 53 is firmly connected with the two supports and is used for maintaining them at a predetermined distance one from each other. The foundation piece 54 carries the base of the column 53 and supports the entire radiator structure upon the ground.

The conducting metallic surfaces of the pipes or tubes 5|! are connected in series with each other by resilient supporting pieces or clamps 55. As shown in Figure 7, the two ends 56 and 51 of each of the connecting and supporting pieces 55, are bent in the form of hooks encircling the tubes 50 and maintaining them in the vertical positions upon the supports 5| and 52.

Terminals 58 and 59 are attached to the support 5| and are adapted to be connected to any suitable source of electrical energy not shown in the drawings. The terminal 58 is connected to a clamp 60 which comprises a single hook-shaped resilient member 6|. The resilient member 6| surrounds the upper end of a coated tube 50a, the lower end of which is carried by one of the two hook-shaped members of a clamp 55. The adjacent tube is carried by the second book of the same clamp 55 connected with the support 52, while the opposite upper end of this second tube is carried by the first hook of a clamp 55 attached to the upper support 5|. 7

As shown in Figure 6, all the tubes 50 are connected in series with each other in this manner.

The clamps 55 supporting the metallic tubes 50 are attached to the supports 5| and 52 in a stepped arrangement. The support 5| also carries two clamps 60 and 62 each of which is provided with a single hook-shaped member 6| or 63, respectively. The clamp 60 is connected to the terminal 53 while the clamp 62 is connected to the terminal 53.

Each of the conducting clamps 55 is attached to the insulated support by a bolt 64 passing through a suitable slot 65 formed in the clamp 55. The slot 65 has a somewhat elongated form to enable the clamps to follow conveniently the expansion of the tubes 50 caused by heat developed by these tubes.

The resilient pressure of the hook-shaped members of the clamps is sufiicient to keep the tubes 50 in their respective positions. Furthermore, these hook-shaped members assure an excellent electrical connection between the clamps and the coated metallic surfaces of the tubes 50.

The tubes 5|] are open at both ends so that heated air can circulate conveniently through the interior of the tubes and around them, as indicated by arrows in Figure 5.

Since there is no permanent connection between the tubes and the clamps holding these tubes, such, tubes which may have become cracked or broken may be conveniently removed and replaced by new ones.

The radiator, illustrated diagrammatically in Figure 8 of the drawings, comprises a plurality of vertical tubes 10 arranged concentrically around a column 12 and carried by supports II. The supports 1| may consist of one or more separate pieces located one over the other and held together by the column 12 supported by the base 13. Clamps of the same type as the clamps 55 shown in Figure 7. may be used for connecting the pines 10 in series with each other The radiator shown in Figure 9 comprises a plurality of horizontal tubes carried by vertical supports 8|, one of which is shown in the drawings. The tubes 80 consisting of glass pro vided with a metallic coating may be inter-connected in series by strips 82 made of a conducting material and carried by the insulating supports ill.

The tubular resistances illustrated in Figures 5, 8 and 9, make it possible to construct radiators or heating devices having a comparatively large heating surface. These radiators operate very smoothly and have a comparatively low temperature while their calorific power is quite high. Due to the tubular form of the heat radiating elements, the thickness of these elements is comparatively small as compared to heating elements consisting of flat plates.

Since comparatively thin glass tubes may be used for these radiators, the manufacturing costs of this type of radiator are very low.

When vertical resistances are used, the tubular form of these resistances makes it possible to provide an excellent circulation of air, since the glass tubes operate as drawing chimneys.

When the tubes are disposed horizontally, a good ventilation may be obtained by placing the tubes in quincuncial arrangement.

In the modifications shown by way of example in Figures fi, 8 and 9 in the drawings, the tubes are provided with a metallic coating only upon their exterior surfaces. It is possible, however, to employ glass tubes, the inner surfaces of which are also coated by a metallic layer. The inner surfaces of the tubes may be conveniently coated by using any pulverizer of suitable form not shown in the drawings, which is placed into the interior of the tubes and which is moved within the tubes.

In certain instances, it may be advisable to eliminate the outer metallic coating altogether and to coat merely the inner surfaces of the tubes as well as those portions of the outer surfaces which are in contact with the hook-shaped members of the clamps supporting these tubes.

In the modification shown in Figure 9a, the tube 90 is provided with an inner coating 9I. The edge of the tube is also provided with a metallic coating 92. Only those portions of the outer surfaces of the glass tube 90 which are in contact with the clamps are provided with a metallic coating 93.

When depositing the metallic particles upon the surfaces of the tubes, it is possible to coat the entire surfaces of the tubes or to place the metallic particles in the form of strips or bands covering only a part of the glass surfaces. For instance, it is possible to deposit the metallic particles upon the outer surfaces of each tube in the form of a spiral strip extending from one end to the other end of the tube. Instead of spiral strips, it is possible to use a plurality of strips extending in a direction parallel to the axis of the tube, or any other suitable arrangement may be employed.

The radiators shown in Figures 5, 8 and 9 may be covered by plates or screens not shown in the drawings which should be provided with suitable openings for the circulation of air.

The application of the principles of the present invention to the manufacture of heated wind-shields of motor cars and the like, is illustrated in Figures 10 to of the drawings.

Figure 10 ,shows a wind-shield I00 consisting of the usual sheet of glass. A comparatively thin strip I0 I is provided upon the outer surface of the glass plate I00. This strip is formed upon the glass surface by projecting molten and pulverized metallic particles which are oxidized to a greater or smaller extent depending upon the nature of the gas transporting the metallic particles to the glass surface.

The thin metallic strip IOI does not disturb, to any noticeable extent, the driver who is looking through the wind-shield. The strip IOI surrounds the entire'wind-shield and extends across the wind-shield approximately at the middle thereof. The ends I02 and I03 of the metallic strip IOI are connected to the battery of the automobile and may be attached to any suitable switch not shown in the drawings.

When an electrical current is caused to flow through the metallic strip I III, this current will heat the wind-shield I00, thus preventing the deposition of moisture or ice upon this windshield.

The wind-shield IIO, shown in Figure 11, comprises two metallic strips III and H2. The strips I II may be placed upon the outer surface of the wind-shield while the strip II2 may be situated upon the inner surface thereof which is nearest to the driver. The ends of the strip III are connected to the terminals H3 and H4, while the ends of the strip II2 are connected to the terminals H5 and H6. The two strips III and H2 may be inter-connected in parallel or in series and are both connected to the battery of the automobile. I

The arrangements of the strips upon the two surfaces of the automobile wind-shield I I0 create the impression of a grid-work which does not disturb the field of vision of the driver or of the person sitting next to the driver.

Figures 12 and 13 illustrate a wind-shield I20, the upper edge 'of which carries a movable slide I2I supporting a sheet of glass I22 which extends parallel to the wind-shield I20. The glass sheet I22 carries a metallic strip I23 formed by projecting metallic particles upon one or both surfaces of the glass sheet I22. The two ends of the metallic strip I23 are connected by terminals I24 and I25 to the battery of the automobile.

When there is danger that moisture or ice may be deposited upon the surfaces of the wind-shield, the terminals I24 and I25 are connected with the battery so that an electrical current will flow through the strip I23. The heat emitted by the strip I23 will be transmitted to the wind-shield I20 melting the ice already formed upon the glass surfaces and preventing the formation of any new ice coatings. The sheet of glass I22 may be removed as soon as the danger of the formation of ice is passed.

The wind-shield I shown in Figs. 14 and 15 carries two terminals I 3| and I32. Terminal I3I is connected with a comparatively short strip I33 carried by the inner surface of the wind-shield I30. The terminal I32 is connected with a similar strip I34. The movable sheet of glass I35 comprises a metallic strip I 36 connected with two conducting leaf springs I31 which are adapted to come in contact with the strips I33 and I34.

This device operates as follows:

When ice begins to form upon the wind-shield, the sheet of glass I35 which is movable relatively to' the wind-shield I30, is shifted to such position that the springs I31 of the metallic strip I36 are brought in contact with the strips I33 and I34 carried by the wind-shield I30. Then, an electrical current is caused to flow through the terminal I3I, the strip I33 carried by the windshield, one of the springs I37, the strip I36 carried by the movable plate I35, the strip I34 carried by the wind-shield, the other one of the springs I31 and the terminal I 32. The heat generated by the metallic strip I36 will melt the ice formed upon the wind-shield I 30. In order to interrupt the flow of the electrical current, it is merely necessary to shift the movable glass plate I35 to a different position thereby interrupting the connection between the metallic strip I30 and the terminals I3I and I32 which are connected with the battery of the automobile.

What is claimed. is:

1. The method of manufacturing electrical resistances, which comprises tempering a glass surface and projecting a jet of gas carrying particles of a molten and pulverized conducting metal upon said tempered glass surface and depositing said particles in the form of a continuous strip Ill) ill)

which is adapted to be heated by an electrical current. i

2. The method of manufacturing electrical resistances, which comprises providing a vitreous surface, and projecting particles of a molten and pulverized conducting metal upon said vitreous surface, said particles being carried to said vitre ous surface by a rapidly flowing stream of an oxidizing gas and being deposited upon said surface in the form of a continuous partly oxidized layer.

3. The method of manufacturing electrical resistances, which comprises projecting particles of a molten and pulverized conducting metal upon a vitreous surface, said particles being carried to said vitreous surface by a rapidly flowing stream of an oxidizing gas and being deposited upon said surface in the form of a continuous partly oxidized layer, and adjusting the length of travel of said particles to provide a metallic layer of a predetermined specific electrical resistance.

4. The method of manufacturing electrical resistances, which comprises projecting particles of a molten and pulverized conducting metal upon a vitreous surface, said particles being carried to said vitreous surface by an oxidizing gas and being deposited upon said surface in the form of a continuous layer, and varying the oxidizing properties of the gas transporting the same, to provide a metallic layer of a predetermined specific electrical resistance.

5. The method of manufacturing electrical rcsistances, which comprises projecting molten and pulverized particles of aluminum carried by an oxidizing gas in the form of a continuous layer upon a tempered glass surface, said particles being oxidized by said gas in the course of their travel, the specific electrical resistance of the layer formed by said particles depending upon the length of their travel and the relative proportions of the metallic particles and the gas.

6. The method of manufacturing electrical resistances, which comprises projecting particles of a molten and pulverized conducting metal upon a vitreous surface, said particles being carried to said vitreous surface by a gas capable of combining partially with the metal during the projection, and being deposited upon said surface in the form of a continuous layer, the specific electrical resistance of said layer being dependent upon the length of the travel of the metal particles and upon the relative proportions of the metallic particles and the gas.

7. An electrical resistance heating element, comprising a tempered glass article carrying a very thin, closely adherent, narrow elongated layer of conducting metal, said layer consisting of conglomerated, partly oxidized, solidified molten metal particles, the ends of said layer being adapted to be connected to a source of electrical energy, said glass being capable of standing high temperatures and rapid changes in temperature without cracking.

8. An electrical resistance heater, comprising a glass article carrying a strip consisting of a mixture of conducting metal and a compound of said metal with a gas said strip being formed by solidifying and conglomerating a thin deposit of finely divided molten metal particles, the ends of said strip being adapted to be connected to a source of electrical energy, said glass being capable of standing high temperatures and rapid changes in temperature without cracking.

9. An electrical resistance heater, comprising a tempered glass article carrying a strip consisting of a mixture of conducting metal and of a compound of said metal with a gas said strip being, formed by solidifying and conglomerating a thin deposit of finely divided molten metal particles, the ends of said strip being adap ed to be connected to a source of electrical energy, said glass being capable of standing high temperatures and rapid changes in'temperature Without crack- 10. An electrical radiator, comprising a plurality of glass plates, each of said glass plates carrying a. strip of conducting partially oxidized metal, said strip consisting of a thin adherent, conglomerated and solidified deposit of finely divided molten metal particles; and m ans supporting said plates and electrically interconnecting the strips carried by these plates, said means being adapted to be connected to a source of electrical energy.

11. An electric radiator, comprising a plurality of tempered glass plates. each of said glass plates carrying a strip of conducting partially oxidized metal, said strip consisting of a thin adherent, conglomerated and solidified deposit of finely divided molten metal particles; and means supporting said plates and electrically interconnecting the strips carried by these plates. said means being adapted to be connected to a source of electrical energy.

12. An electrical heating device, comprising a plurality of glass plates, each glass plate comprising layers of a conductin'g metal deposited in the form of continuous strips on opposite side surfaces of the plate; a support having grooves extending in spaced parallel relationship upon said support, the ends of said plates being adapted to project into said grooves, conducting clamps carried by said support and adapted to hold said plates, and means electrically connecting at least some of said clamps, said clamps being electrically connected with the metallic strips carried by said plates. l

13. An electrical heating device, comprising a plurality of tempered glass plates, each glass plate comprising layers of a conducting metal deposited in the form of continuous strips on opposite side surfaces of the plate; a support having grooves extending in spaced parallel relationship upon said support, the ends of said plates being adapted to project into said grooves, conducting clamps carried by said support and adapted to hold said plates, and means electrically connecting at least some of said clamps, said clamps being electrically connected with the metallic strips carried by said plates.

14. A heating device, comprising a plurality of glass tubes, layers of a conducting metal carried by at least some of the surfaces of said tubes, said layers consisting of a thin adherent conglomerated and solidified deposit of finely divided molten metal particles an insulated support, and clamping means carried by said support and made of a conducting material, said clamping means supporting said tubes and interconnecting electrically the metallic layers of said tubes.

15. A heating device, comprising a plurality of tempered glass tubes, layers of a conducting metal carried by at least some of the surfaces of said tubes, said layers consisting of a thin adhercnt conglomcrated and solidified deposit of finely divided molten metal particles an insulated support, and clamping meanscarried by said support and made of a conducting material, said clamping means supporting said tubes and interconmeeting electrically the metallic layers of said tubes.

16. A window or windshield for automobiles or the like, comprising a tempered glass plate and a comparatively narrow strip of conducting metal carried by at least one surface of said plate, said strip consisting of a thin adherent conglomerated and solidified deposit of molten metal particles, the ends of said strip being adapted to be con- 10 nected to a source of electrical energy.

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