In the course of a communication presented to the Societe Industrielle du Nord de la France by the manager of the Wazemmes Gas Company, he made the following remarks on gas lighting with high-power burners:
For gas of a standard illuminating value, the lighting power increases with the temperature of the flame. It also increases, under favorable conditions, if the quantity of gas consumed by the burner in a certain period is augmented. Thus, two burners consuming 60 liters (rather more than 2 cubic feet) of gas, placed in juxtaposition, produce less light than one burner consuming 120 liters. As it is impossible to indefinitely increase the supply to ordinary burners, multiple-flame burners have been invented, in which two or more ordinary flames are united so that they may impinge upon each other. By an ingenious arrangement for bringing the air into contact with the multiple flames, two excellent types of lamps are obtained, consuming respectively 700 and 1,400 liters per hour, which meet with a rapid demand in Paris, and in many other towns, for lighting wide public thoroughfares, squares, and large open spaces. If, however, it is desired to obtain a flame with a much higher temperature, it is necessary to resort to a special arrangement for heating the air intended for combustion with the gas.
The principle of heating the air by means of waste heat escaping with the products of the waste gas - the regenerative principle - was adopted by Mr. F. Siemens, and applied not only to gas burners, but to high temperature stoves. With the Siemens burner on the regenerative principle the following results are obtained: With a consumption of 150 liters per hour, the light of from 1 to 3 carcels; 250 to 300 liters, 6 to 7 carcels; 600 liters, 15 carcels; 800 liters, 20 to 22 carcels; 1,600 liters, 46 to 48 carcels; 2,200 liters, 72 carcels. Unfortunately, the construction of the Siemens Argand lamps is very delicate, and, moreover, they have the disadvantage of being heavy and rather unsightly. In Germany they have been widely adopted; but in France they have met with but little success. The Schulke lamp is made on the same principle; and this appears to be too delicate to come into general use. One of the latest burners of the regenerative class is the Wenham, which has been before the public for some time in England and is now being adopted in France. In point of fact it is merely a very effective improvement on Breittmayer's burner, from which it differs only in its construction; being produced in some elegant styles, which lend themselves perfectly to the decorations of private houses.
The No. 2 lamp of this type, with a consumption of 283 liters (10 cubic feet) per hour, has given 126 candles, in a vertical direction without reflectors: horizontally, 50 candles. But the gas employed in the tests had an illuminating power about 20 per cent. higher than that usual in Paris. When experimenting in Paris with a No. 3 lamp in a vertical direction, it showed a consumption of 34.6 liters (1.2 cubic feet) per carcel obtained. The Wenham lamp is constructed to give light in a vertical direction; and by adopting a large reflector, the illuminating power is increased 18 per cent. in a vertical line and 55 per cent. at 80°, which is a highly satisfactory result. There are at present five sizes of these lamps. There is also the Delmas hot air burner, in which the batswing flame is completely inclosed in a glass, mounted with a sheet-iron casing, heated by the products of combustion, through which the air passes on its passage downward to feed the flame; and it thus increases the temperature, improves the illuminating power, and produces a beautiful steady light. Mention also may be made of the Siemens radiated heat burner, by means of which the heating of the air is effected simply by the radiation of the metallic parts of the appliance which are in contact with the flame.
These burners produce the light of 1 carcel (9.5 candles) with a gas consumption of 70 liters (about 2½ cubic feet), and are therefore, from an economical point of view, intermediary between the high power and regenerative burners. This degree of economy can be ascertained by an ingenious arrangement of the air supply in a burner with holes, which has been made in in the laboratory of the Wazemmes Gas Company by M. Verlé, the engineer, who has invented a very simple burner called the "Lillois," with which the light of 1 carcel is obtained with a consumption of 70 liters. This produces a tulip-shaped flame, and it has a specially constructed glass arrangement on the outside for regulating the combustion. Comparing the above-mentioned burners with each other, we arrive at the following results: The "Lillois" burner consumes 70 liters of gas per carcel; the Siemens ordinary, 70 liters; the Siemens-Breittmayer, 35 to 39 liters; the Wenham, about 35 liters. Taking this into account, and considering that a carcel corresponds with 105 liters of gas consumed in the Bengal form of burner, we see that the economy in gas might, by employing these burners, reach from 33 to 71 per cent.
If this is compared with the batswing burner, which produces the light of 1 carcel with a consumption of 120 liters of gas, the economy is greater - varying, according to the type of lamp, from 41 to 85 per cent.