36 Occurrence of the Element Gallium in Clay-Ironstone. 



form the subject of another communication dealing with the chem- 

 istry of the process. 



Some of the photographs were remarkably fine in definition, and 

 they extended from the less refrangible limit of the red rays to the 

 ultra-violet, about wave-length 3240. 



It may be mentioned here, however, that every line and band in 

 the different spectra was identified. Some of the photographs 

 afforded evidence of very unusual constituents in the mixture of 

 gases and vapours, which by their combustion and incandescence 

 give the Bessemer flame. The identity of these could have been 

 established only by means of very complete investigation of oxy- 

 hydro"en blowpipe spectra. Apart from all technical considera- 

 tions which were kept in view, and of such purely scientific questions 

 as were involved in similar previous researches carried out by one of 

 us, the examination of these spectra was of great 'interest, more 

 especially because of the proof of the rare element, gallium, being- 

 present in the Bessemer metal, and in the roasted ore from which 

 it was extracted. It was shown by very careful analyses that the 

 gallium was concentrated in the iron, but all details of the operations 

 involved in its separation and of the quantitative determinations are- 

 reserved for a future communication. 



The evidence of the existence of gallium in the ore and in the 

 metal rests on the measurements of the wave-lengths of the lines in 

 a large number of photographed spectra and upon the relative 

 strengths of the lines in the different materials examined and in the 

 precipitates obtained therefrom. 



The following examples show the nature of this evidence : 



1. Evidence from the Bessemer Flame Spectra. 



Seventy-six of the photographed spectra of the Bessemer flame 

 contain a strong line with wave-length about 4171'5, which does not 

 appear to be related to any other line in these spectra, and belongs, 

 therefore, to some other element than those otherwise identified. 



2. Evidence from the Spectrum of the " Mixer Metal " and of the 

 different substances separated by its Chemical Treatment. 



The " mixer metal " heated in the oxy-hydrogen flame gives a 

 spectrum of iron with a strong line having a wave-length of 417T6. 



The residue left after dissolving the iron by boiling with hydro- 

 chloric acid also gives this line 4171*6 very strongly. 



Precipitates obtained by boiling the solution of the iron with am- 

 monium acetate give the line 41 71 '6 and also a weaker line, wave- 

 length 40327. 



