On the unknown Lines in the Spectra of certain Minerals. 133 



On the unknown Lines observed in the Spectra of certain 

 Minerals." By J. NORMAN LOCKYER, C.B., F.R.S. Received 

 May 16, Read June 4, 1896. 



In the first note of the series " On the New Gases ohtained from 

 Uraninite," by the distillation method, I remarked* " I have already 

 obtained evidence that the method I have indicated may ultimately 

 provide us with other new gases, the lines of which are also associated 

 with those of the chromosphere." 



In a subsequent paper " On the Gases obtained from the Mineral 

 Eliasite," I gave a list of several lines unknown to me, and suggested 

 that they might indicate the existence of a new gas or gases in that 

 mineral, and I addedf " Although the evidence in favour of a new 

 gas is already very strong, no final verdict can be given until the 

 spectra of all the known gases, including argon, have been photo- 

 graphed at atmospheric pressure, and the lines tabulated. This part 

 of the inquiry is well in hand." 



The inquiry above referred to has now been completed and in the 

 following manner : 



Photographs were taken of the spectra at atmospheric pressure of 

 nitrogen, oxygen, chlorine, carbonic anhydride, coal gas, sulphuric 

 anhydride, phosphoretted hydrogen, and argon, these being the 

 gases which, from the experience thus far acquired, are likely to be 

 associated with those given off by minerals. In addition to these, 

 the lines of mercury, potassium, and platinum, were also photo- 

 graphed. The lines of platinum are always present in the spectra 

 for the reason that the spark is passed between platinum poles, while 

 the lines of mercury or potassium frequently appear according as the 

 gases are collected over mercury or potash. 



The spectroscope employed has a collimator and camera with 

 object glasses of 3 in. aperture, and focal lengths of 5 ft. and 19 in. 

 respectively. Two prisms of 60 were used, giving a length of 

 spectrum of about 1*75 in. between K and D. 



In order to facilitate the reduction of the photographs, the solar 

 spectrum was photographed under exactly similar instrumental con- 

 ditions. Micrometric measures were made of H and K, and other 

 well-known lines throughout the spectrum, and by means of these 

 and Rowland's wave-lengths, a curve was carefully constructed. 



It may be incidentally mentioned that in the photographs of the 

 spectra of gases at atmospheric pressure, H and K are generally 

 present as pole lines, being probably due to an impurity of calcium 

 in the platinum poles. 



* ' Eoy. Soc. Proc.,' vol. 58, p. 70. 

 t ' Roy. Soc. Proc.,' vol. 59, p. 3. 



