FLAMES OF ATOMIC HYDROGEN 



137 



molecular hydrogen 21.8 per cent, and atomic hydrogen 17.3 per cent by 

 volume. 



There is another factor which tends greatly to increase the temperature 

 of the atomic h}'drogen flame even above the calculated value of 4030° K. 

 The atomic hydrogen, instead of being originally at room temperature, is 

 already at a high temperature at the moment of its escape from the arc. The 

 conditions are analogous to those in an oxyhydrogen flame in v^hich both 

 gases are preheated. Thus the upper limit of temperature is fixed only by 

 the degree of dissociation of the hydrogen and the rate at which heat is lost 

 by radiation or contact with bodies of lower temperature. 



RATE OF SURFACE HEATING BY FLAMES 



Although the high temperature of the atomic hydrogen flame is of great 

 importance when it is desired to melt substances of very high melting point 

 such as tungsten, a factor of even greater importance in ordinary welding 

 operations is the rapidity with which heat can be delivered to a surface per 

 unit area. 



TABLE II 

 Rate of Surface Heating Produced by Various Flames 



Watts/ sq. cm. 



(i) Ordinary Bunsen burner (gas-air) at tip of inner cone. Flame 

 15 cm. high, cone 4.5 cm. high 



(2) Ordinary blast lamp (gas-air), 14 cm. from burner tip in flame 



25 cm. long, nozzle 0.60 cm. diameter 



(3) Same at 19 cm. from burner tip (hottest part) 



(4) Ordinary blast lamp (hydrogen-air), 13 cm. from burner tip 



(5) Blast lamp for quartz blowing (gas-oxygen) 2.5 cm. from burner 



tip 



(6) Same with hydrogen-oxygen 



(7) Acetylene welding torch, adjusted for maximum effect (several 



different tips gave about the same result) 



(8) Atomic hydrogen flames : 



51 



57 



72, 



100 



450 

 520 



670 



Amperes 

 20 



40 

 60 



Volts 

 100 



75 

 65 



Mm. from tips 



3 



5 

 7 

 3 

 5 

 7 

 10 



5 



7 



10 



15 

 20 

 30 

 40 

 SO 



580 

 640 

 400 



TOOO 



II40 

 900 

 620 



1300 



IIOO 



850 

 500 

 330 



190 

 130 



95 



