PHYSICS. 349 



only 0.0032, a strip of platinum of the same dimensions would, on a simi- 

 lar supposition, be wanned in one second to 2,603° C, a temperature suf- 

 ficient to melt it. {Proc. Am. Acad., January, 1881, xvi, 342 ; Nature, 

 July, 1881, xxiv, 294.) 



Siemens, in a lecture at Glasgow, has considered the question of gas 

 and electricity as heating agents. The object which he set before him- 

 self was to prove that, for all ordinary i)urposes of heating and melting, 

 gaseous fuel should be resorted to, for the double reason of producing 

 the utmost economy, and of doing away with the bugbear of the pres- 

 ent day, the smoke nuisance; but that for the attainment of extreme de- 

 grees of heat the electric arc possesses advantages unrivaled by any 

 other source of heat. In support of the economy of gaseous fuel, he 

 found that under the boiler of the steam-engine only 1,282 units of heat 

 were obtained from one pound of coal, instead of 10,500, and in the melt- 

 ing of steel only 1,800 heat units are obtained from 2.5 pounds of coke, 

 instead of 32,625 units, the actual value. In domestic use the waste is 

 even greater, but it is not possible to determine it exactly. This waste 

 led him to devise his smokeless grate, in which a fire of coke is fed with 

 coal-gas. His oflice was perfectly warmed by the consumption of 02 

 cubic feet of gas, and 22 jjounds of coke per day of nine hours, at a cost 

 of 47 pence. The use of gas for heating is greatly to be encouraged. 

 The electric furnace for melting steel was exhibited, and eight pounds 

 of files were melted and poured into an ingot before the audience. A 

 current of 70 amperes, produced by an expenditure of 7-horse power, 

 and which would give a light of 12,000 candles, sufiiced to raise an 8- 

 iuch crucible to a white heat in fifteen minutes, and in a second fifteen 

 minutes to fuse four pounds of steel. {Nature, February, 1881, xxiii, 

 327,351.) 



Terquem has studied the constitution of the Bunsen flame, and has 

 suggested some modifications in the form of the lamp. The ordinary 

 flame has a hollow cone in the center, so that its heating effect is much 

 reduced. If more air be admitted for the purpose of remedying this 

 defect, the flame becomes solid, but very unsteady, and soon strikes down 

 within the tube. The author has succeeded (1) in making the flame less 

 unsteady, (2) in mixing with the gas the maximum quantity of air that 

 the gas requires, without lighting below, and (3) in obtaining tliis re- 

 sult with tubes of all diameters up to 4 centimeters, whatever be the 

 pressure of the gas. These objects arc obtained: 1st, by dividing the 

 opening whence the gas issues into several sectors, by two or more ver- 

 tical partitions fixed on the sides and ])assinginto the tube; and, 2d, by 

 placing in the center of the tube a small plate or a ball which thus makes 

 the orifice annular. The flame is thus made solid throughout, is very 

 hot, and the tube can be rai.sed ibr a decimeter above the gas-jet without 

 having the flame strike down through it. {J. Phys., March, 1881, x, 119.) 



