126 PHENOMENA, ATOMS, AND MOLECULES 



ducing action of the atomic hydrogen, alloys containing chromium, 

 aluminum, silicon or manganese can be welded without fluxes without 

 surface oxidation. The rapidity with which such metals as iron can be 

 melted seems to exceed that in the oxy-acetylene flame, so that the process 

 promises to be particularly valuable for welding. 



The technical development of these welding processes using flames of 

 atomic hydrogen has been the work of several men, among whom Robert 

 Palmer and R. A. Weinman must be particularly mentioned. Papers 

 describing the apparatus used and the results obtained will soon be 

 published by Mr. Weinman and the writer in the General Electric Revieiv. 



Mr. P. Alexander, following out a line of development suggested by 

 Professor Elihu Thomson, has independently arrived at an arc welding 

 process utilizing hydrogen for the purpose of improving the ductility of 

 the weld and the speed of operation. In this process the arc is passed 

 between an iron electrode and the material to be welded. This process also 

 depends at least in part on the use of the high heat conductivity of atomic 

 hydrogen. 



Some joint work of Mr. Alexander and the writer has shown that 

 particular advantages are obtained in some cases by using mixtures of 

 nitrogen and hydrogen, and that the quality of the weld is not impaired by 

 nitrogen unless oxygen is also present. A paper by Mr. Alexander describ- 

 ing his process will appear simultaneously with those dealing with the 

 atomic flame process. 



PART THREE 12 



The heat carried away from an incandescent wire by a surrounding 

 inert gas at ordinary temperatures increases roughly in proportion to the 

 1.9*^^ power of the absolute temperature, T, of the filament.^ This relation 

 holds, for example, for such gases as nitrogen, argon, and mercury vapor 

 up to the temperature of melting tungsten, 3660° K. In the case of 

 hydrogen, however, abnormal results were obtained in experiments made 

 at high temperatures. Up to about 1700° K. the normal exponent of 

 1.9 was observed, but at higher temperatures the exponent increased until 

 at 2600° K. and above it was about 5.0. At 3400° K. the heat conducted 

 by hydrogen was twenty-three times as great as that carried by nitrogen 

 under similar conditions. 



* Received April 19, 1927. A major part of the subject matter of this paper was 

 covered in an address under the same title delivered at the General Meeting of the 

 American Chemical Society, Philadelphia, Pa., September 8, 1926. Preliminary 

 publications have appeared in the Gen. Elec. Rev., 2g, 153, 160 (1926). 



^Langmuir, Trans. Am. Electrochcm. Soc., 20, 225 (1911) ; Phys. Rev., 34, 401 

 (1912) ; Jour. Amcr. Chem. Soc, 34, 860 (1912). 



