218 



Profs. G. D. Liveing and J. Dewar. [Feb. 19, 





The gases were supplied from steel cylinders into which they had 

 been compressed, and the pressure was registered by a gauge attached 

 to the tube by which the gas entered the experimental cylinder. 

 Commercial compressed gases were used, containing a sensible per- 

 centage of air. 



When hydrogen was the gas forming the burning jet, it was 

 lighted at the end of the tube 6 before introducing it into the 

 experimental cylinder. When it was desired to have a jet of oxygen 

 burning in hydrogen, this could be managed by introducing oxygen 

 through the second tube and increasing the supply of hydrogen until 

 the flame passed over to the oxygen jet. The same result was some- 

 times attained by first filling the experimental cylinder by a gentle 

 stream of hydrogen "through the side tube c before the end with the 

 tube ft was screwed on ; the hydrogen as it issued was then lighted, 

 and the jet, with a gentle stream of oxygen issuing, inserted and 

 screwed down. The stopcock s was kept open until this was done, 

 and then by closing s, and admitting more gas from the reservoirs, 

 the pressure in the ^experimental cylinder oould be increased at 

 pleasure. 



Hydrogen Burning in Oxygen. 



The first observations were made with a jet of hydrogen burning 

 in oxygen. As the pressure rose, the luminosity of the flame in- 

 creased, as long ago described by Frankland (' Experimental 

 Researches,' p. 905). The colour of the flame, viewed end on, was 

 yellow, as if it contained sodium ; but, on examining it with a 

 spectroscope, it was found to give a continuous spectrum intersected 

 by many shaded bands, and the D lines of sodium were only faintly 

 present. The shaded bands were faint at a pressure of 5 atmo- 

 spheres, but at pressures of 20 atmospheres and upwards they came 

 oat strongly. They were evidently the absorption bands of N0 





