FLAMES OF ATOMIC HYDROGEN 125 



tube became heated to incandescence, although no electric current flowed 

 through this tube and the glass walls near the wires were not heated 

 strongly. These effects were nearly absent when the hydrogen was carefully 

 dried. In correspondence with Professor Wood, the writer suggested that 

 these effects were due to high concentrations of atomic hydrogen which 

 could accumulate in the tube because of the effect of water vapor in 

 poisoning the catalytic activity of dry glass surfaces that otherwise 

 destroyed the atomic hydrogen. With moisture present the atomic hydrogen 

 diffused through the side tube and the atoms combined to form molecules 

 on the surfaces of the metallic wires which acted as catalysts. 



Shortly after this correspondence it occurred to the writer that it should 

 be possible to obtain even higher concentrations of atomic hydrogen by 

 passing powerful electric arcs between tungsten electrodes in hydrogen at 

 atmospheric pressure. The high heat conductivity of the gas due to the 

 energy liberated by the recombination of the rapidly diffusing atoms should 

 prove of particular value in the construction of electric furnaces, and for 

 melting metals in general. Experiments of this kind were soon made. 

 Twenty ampere arcs from a constant current transformer were passed 

 between two tungsten rods 6 mm. in diameter mounted transversely in an 

 alundum tube (lo cm. diam.) through which a stream of hydrogen flowed 

 and burned at the open end. 



Arcs up to 2. cm. in length were obtained with voltages ranging from 

 300-800. The arc, of a beautiful red color, was of small diameter (about 

 3 mm.) and was bowed out into a fan shape by its own magnetic field. 



Iron rods 2 or 3 mm. in diameter melted within a couple of seconds 

 when they were held 3-5 cm. above the arc. By directing a jet of hydrogen 

 from a small tube into the arc, the atomic hydrogen could be blown out of 

 the arc and formed an intensely hot flame of atomic hydrogen burning to 

 the molecular form and liberating 90,000 calories per gram molecule— 

 about 50 per cent more than that in an oxy-hydrogen flame. To maintain 

 these conditions the electrodes had to be brought closer together (prefer- 

 ably 1-3 mm.). 



In this flame, even at distances of i to 2 cm. from the arc, it was found 

 that molybdenum melted with ease, and tungsten rods of 3 mm. diameter 

 could be melted when held very close to the arc itself. Quartz, on the other 

 hand, melted with more difficulty than molybdenum, indicating that the 

 catalytic action of the metals played an important part in the rapidity with 

 which they could be heated. 



The use of hydrogen under these conditions for melting metals has 

 proved to have many advantages. Iron can be welded or melted without 

 contamination by carbon, oxygen or nitrogen. Because of the powerful re- 



