354: Browning and Uhler — Gallium-Indium Alloy. 



sequently veriiied by numerous exposures with much purer 

 material in the crater of the arc. There is a new band spectrum 

 due either to gallium or to gallium oxide (but very probably 

 due to the gallium molecule) the wave-lengths of the heads of 

 which are roughly 3889, 3778, 3677, 3586 (?), 3495, and 3415. 

 The head near 3586 is partially concealed by the 3590 band 

 usually ascribed to cyanogen. The band commencing at 3889 is 

 by far the strongest and has a very sharp, well-defined edge. 

 The intensity of the successive bands decreases as the wave- 

 length becomes smaller. Moreover, the heads of the fainter 

 bands are not sharp, but this may be due to underexposure. 

 On the other hand, the individual bands shade off toward the 

 red. The dispersion and resolving power are so low that there 

 seems to be no separation of the bands into fine lines. These 

 bands extend a relatively long distance and appear, at first 

 glance, to form a continuous background to the entire region 

 from 34:15 to 4000. The cyanogen bands, on the contrary, 

 show fine line structure even in the first order. 



A series of eleven lines occurs between 3890 and 4030. 

 These lines are comparatively fine and close together, and 

 separate more and more as the frequency increases. The 

 group probably constitutes the heads of a set of fine bands 

 which are narrow and shade off toward the less refrangible 

 side. Various careful tests show that indium is not responsible 

 for the production of any of the bands mentioned above. 

 Both sets of bands seem to be best developed when the gallium 

 is first heated in the arc and the metallic vapor is evolved 

 copiously. 



In addition to the lines recorded by earlier investigators, the 

 negatives of the purest specimens of gallium which we have 

 so far been able to produce contain lines at XX 2259, 2294, 

 2338, 2371, and 2418. These lines have the character of the 

 heretofore known gallium lines and they certainly do not per- 

 tain to any of the impurities such as copper, indium, lead, 

 silver, tin, zinc, etc. An attempt to discover a hypothetical 

 ultra-violet absorption spectrum of the vapor of gallium failed. 

 It is highly probable that this negative result was due to the 

 fact that it was not feasible to heat the large silica bulb used 

 to a higher temperature than was produced by the flame of a 

 Meker burner. As soon as possible the wave-lengths of the 

 gallium lines will be accurately determined by means of a 

 21 ft. grating so that the constants of- the series formula may 

 becalculated independently of the analogous data for alumin- 

 ium, thallium, indium, etc. 



The authors wish to make acknowledgment to Dr. W. F. 

 Hillebrand of the Bureau of Standards, who first called their 

 attention to the existence of this alloy. 



Yale University, New Haven, Conn., March, 1916. 



