122 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1918. 



light. Clouds prevented him from trying the experiment that after- 

 noon, but the next morning he completed the necessary adjustments 

 and drawing his spectroscope toward that portion of the sun's edge 

 where the day before the most brilliant prominences had been seen 

 during the eclipse, he found that the same lines came out again 

 clear and distinct. Now he could study them at his leisure, not 

 hurried by the quick rush of the eclipse phenomena, and he de- 

 termined accurately the positions of the lines in the spectrum. He 

 immediately confirmed his first conclusion that hydrogen is the 

 most conspicuous of the prominence materials, but found that the 

 yellow line which had been attributed to sodium was slightly dis- 

 placed from the position of the real sodium lines and must probably 

 be the revealed characteristic radiation of a new chemical element. 



Messrs. Lockyer and Frankland confirmed the results of Janssen, 

 and proved definitely that the yellow line could not be ascribed to 

 the spectrum of any known terrestrial element. Frankland pro- 

 posed for the new discovery the name of " helium," from the Greek 

 " helios," the sun, and this name has been universally accepted for it. 



After some years the yellow line of helium and some others which 

 appeared to be associated with it were detected in the spectra of 

 some of the stars. These lines are found as dark absorption lines in 

 the spectra of the Orion stars, but bright in the spectra of certain 

 others, and both bright and dark in the spectra of some of the so- 

 called new stars. 



Much searching was done to find this new element upon the earth, 

 but, until 1895, without success. In that year Dr. Ramsay, a collabo- 

 rator with Lord Rayleigh in the discovery of argon in the atmos- 

 phere, made an examination of the gas given off on digesting with 

 acid specimens of Norwegian cleveite. He found in this spectrum 

 the conspicuous yellow line of helium as theretofore known in the 

 sun. Associated with helium he found also argon and other gases. 

 Cleveite is a species of pitch-blende and is one of the ores of uranium. 

 It was soon found that the gas helium was quite widely distributed 

 upon the earth, though in minute quantities, and was found in other 

 ores of uranium and also in the gases given off by certain mineral 

 springs, even found free in the atmosphere in traces, and was also 

 to be found associated with natural gas in the gas wells of the United 

 States. It was also found in meteoric iron. 



Of course the spectrum and all the properties of the new element 

 Avere carefully studied, and it was found to be an inert chemical. 

 Its molecule contains but one atom, whereas hydrogen and oxygen 

 molecules have two. The greatest efforts have been made to cause 

 it to combine with other chemical elements. Every device known to 

 science has been employed, but without success. No combinations 

 whatever can be made between helium and any other known chemi- 



