242 



REPORT — 1880. 



suitable manner, one in wliicli air is supplied too slowly, and the other in 

 -which it is too rapidly mixed with the gas. As in flat-flame burners the 

 air supply is chiefly regulated by means of the pressure under which the 

 gas is allowed to issue, it is necessary to avoid these two extremes in order 

 to develop the light-giving properties of the gas. The dimensions of the 

 orifice through which the gas issues from such burners, and the velocity 

 with which it issues, should be so adapted to each other that the gas in 

 burning is brought into contact with air in such a manner that the heat 

 developed from a portion of the burning gas heats the remainder to a high 

 state of incandescence before it is ultimately entirely oxidised. The 

 quality of a flat-flame burner depends almost entirely on the extent to 

 which this condition is fulfilled. Tn Argand burners, or at any rate in 

 those of the best consti-uction, the due supply of air is admitted to the 

 interior and exterior of the cylinder of flame, and regulated by means of 

 the chimney and cone, the gas being allowed to issue from the burner 

 under little or no pressure. A more complete control is thus obtained 

 over the air supply than is possible in the case of flat-flame burners, and 

 it is probably on this account that more light can be developed from com- 

 mon gas when burned in good Argand burners than when burned in 

 ordinary quantities in flat-flame burners. 



The efiect of the pressure under which gas is caused to issue upon 

 the air supply, and consequently upon the amount of light emitted, is 

 shown in the following results of experiments made with union-jet and 

 batwing burners having orifices of various dimensions and unprovided 

 with any means of checking jiressnre. The gas was caused to pass 

 through them under different pressures applied by means of a weighted 

 gas-holder. 



The gas used was equal to 16 candles when tested with the standard 

 burner — Sugg's No. 1 London Argand. 



Union-Jet Burners. 



