GAS-FURNACE 595 



GAS-ENGINE (Lenoir' s patent). From time to time various forms- of 

 explosive engines have been introduced. Lenoir's is one of this description which 

 has engaged the public attention ; it differs in principle but little from those gas-engines 

 by which it has been preceded. 



It resembles a horizontal steam-engine in outward appearance, but the motive 

 power is obtained by exploding a mixture of coal-gas and air on each side of the 

 piston. The explosion is effected by means of a small galvanic battery, which is 

 alternately put in circuit with wires at either end of the cylinder by means of an 

 insulated conductor sliding on the cross head of the piston. Two slide valves are 

 employed, driven by excentrics in the usual manner ; one serving for the admission 

 of the mixed gases, whilst the other covers the ports, for the removal of the gases pro- 

 duced by the explosion. The cylinder is kept cool by a current of water, which cir- 

 culates about its outer surface. 



From a report on the mechanical effect produced by this engine, published by 

 M. Tresca, the following data have been obtained : 



The hourly consumption of gas per effective H. P. is 1017 cubic feet. The ignition of 

 the gases in the interior of the cylinder is effected at a temperature of 536 Fahr. 

 and 175 gallons of water, at 64 Fahr. are employed per hour in cooling the cylinder, 

 the temperature being raised by the contact of the heated metal to 105 Fahr. 



It will therefore be seen that there is no economy to be obtained from the use of 

 this engine in the place of steam-power, but it may be conveniently employed for the 

 production of a small power in places where it is considered desirable to dispense 

 with the use of steam boilers. Another, and perhaps more formidable objection, is 

 pointed out by M. Tresca in the fact, that a trace of nitric acid is invariably found 

 in the products of the explosion, which results from the oxidation of a minute 

 quantity of the nitrogen in the air employed, and which is likely to exert a destruc- 

 tive influence on the interior of the cylinder. 



The gas-engine known as the moteur Lenoir, which was imagined at the commence- 

 ment of the present century by an engineer named Lebon, was intended to supply 

 motive power in small workshops ; the Lenoir engine has answered the end for which 

 it was invented, and has carried motive power into the very residence of the workman. 

 The Lenoir engine has no boiler; it is fed by a current of ordinary gas, mixed 

 with a certain amount of air ; an electric spark, produced from a Kuhmkorff coil, 

 excited by the machine itself, sets fire to the mixture, and the heat which results is 

 the true motive power of the engine. The Lenoir engines are of the force of one-half 

 to three-horse and they occupy little space ; amongst their advantages are, that they 

 can be started and stopped instantaneously, and present no danger from explosion 

 or fire. They require to be kept, however, in perfect condition, otherwise they are 

 liable to sudden and apparently unaccountable stoppages. 



With regard to their economy, according to experiments made with an engine 

 having a cylinder 0'24 meter in diameter, and a stroke of 0*12 meter, the gas used 

 amounted to from 2,699 to 5,352 litres per horse per hour, but the consumption in 

 regular working is about 2,700 litres. The most economical employment corresponded 

 with a little less than the force of one horse, the speed of the flywheel being 107 

 revolutions per minute. The consumption of water was equal to 120 litres per horse 

 per hour ; this water left the cylinder at a temperature inferior to 100 C. 



There is another class of machines about which a few words should be said ; their 

 applications are not yet numerous, but they doubtless have a great future before 

 them ; these are compressed air-engines which allow of work being carried on at the 

 depth of thirty to forty meters below water, and even deeper, for the establishment of 

 the tubular foundations of bridges, and for other purposes. The piercement of Mont 

 Genis offers an admirable example of the new and important means of employment of 

 compressed air. The works of the grand Alpine tunnel have shown with what 

 facility air compressed under six or seven atmospheres can be conveyed through pipes 

 to great distances, as far as five miles or more, without any sensible loss of pressure 

 to work motive machines similar to ordinary steam-engines. See AIB-ENGINB. 



These results are very important, and may contain the germs of the solution of the 

 problem of distributing motive power wherever it is required in towns. We have spoken 

 of the Lenoir engine, but in spite of many improvements introduced into gas motors, 

 they still have their inconveniences ; their power, at the same time, is very limited. 



GAS-FURNACE. Lundiris Gas-Furnace. Puddling with wood is practised to a 

 considerable extent in Sweden, the best furnace being that of F. Lundin, of Carlstadt 

 Munkfors, fig. 1058, designed for the consumption of turf and peat without drying, 

 and of wet sawdust or other moist fuel. A. fig. 1058, is a pile of green sawdust; B, 

 hopper and cone ; D, gas generator for green sawdust; o, condenser; x, air blast; s, 

 chimney, 43 feet high ; Y Y, 3,500 Ibs. of iron in bars, cooled by the water from pipe 



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