THE DISCOVERY OF ARGON AND HELIUM. 19 



through the spectroscope. The first thing we noticed was a mag- 

 nificent briUiant yellow line. The next week Professor Ramsay 

 was going over to France to give an address to the Academie des 

 Sciences in Paris on argon. When on the Friday afternoon we 

 examined this gas from the cleveite, the brilliant yellow line at 

 first suggested the element sodium, for it looked exactly like the 

 sodium line, which is a yellow line, or rather a double one. I at 

 once said the tube must be very dirty. Professor Ramsay said, 

 however, "it is perfectly clean, but it is perfectly easy to test it. 

 Produce the yellow sodium line and compare it, and if the two 

 lines coincide then it is sodium ; if not, it is something else." 

 This was done, and at once we saw that it was not the sodium 

 line, for it was on one side of it, and at once helium was sugges- 

 ted. The reason for that was, that about thirty years ago, during 

 an eclipse of the sun, Professors Frankland and Norman Lockyer 

 made a large number of photographic and spectroscopic examina- 

 tions of the corona — i.e.^ the extreme outside of the sun, the part 

 which is seen only during ecUpses, where great volumes of incan- 

 descent gases are shot out hundreds of thousands of miles in 

 great tornadoes. These examinations of the sun's corona revealed 

 a brilliant yellow line. This yellow line was unknown at the time 

 and corresponded to no known element on the earth, so Norman 

 Lockyer suggested calling it helium. It had been seen at this 

 particular part of the sun. It was of interest, because only the 

 very lightest gases such as hydrogen existed there, and here was 

 another gas, which, presumably, was as hght as hydrogen — existing 

 in the corona of the sun together with hydrogen. 



Nothing more was known of it until, in this gas prepared from 

 cleveite, this yellow line appeared, and we could not be certain 

 that it was helium until we had actually measured the wave-length 

 of that particular line. Professor Ramsay took it up to Mr 

 Crookes that night, and on the Saturday morning Mr. Crookes 

 measured it, and found it was almost, if not quite, identical with 

 the line of helium, D^ ; so that Professor Ramsay was able to 

 telegraph over to the French chemist (Berthellet), saying he was 

 coming over to give the lecture on argon, and that he had dis- 

 covered another new element, helium, which he would bring over 

 with him. 



