136 SIK WILLIAM KAMSAY 



and that it certainly is not. We are making more of it and in a 

 few days I hope we shall have collected enough to do a density. 

 I suppose it is the sought for krypton, an element which should 

 accompany argon. . . . We have settled the question of argon 

 in the animal economy : there is absolutely no trace of argon in 

 peas or in mice. And I have done a good deal as regards density, 

 specific heat and expansion, a paper on which I shall send in to 

 the R.S. for next Thursday." 



The presentation of the paper referred to had to be 

 postponed, for within the week the new gas had been 

 identified. 



The surprise and delight of Ramsay may be conceived 

 when he found that the gas which he obtained from this 

 mineral contained not only argon, but a gas which from 

 its highly characteristic spectrum was recognised as the 

 hypothetical solar element to which the name helium 

 had been given by Lockyer many years before. 



On 24th March he wrote as follows to his wife : 



" Let's take the biggest piece of news first. I bottled the new 

 gas in a vacuum tube, and arranged so that I could see its spec- 

 trum and that of argon in the same spectroscope at the same 

 time. There is argon in the gas ; but there was a magnificent 

 yellow line, brilliantly bright, not coincident with but very close 

 to the sodium yellow line. I was puzzled, but began to smell 

 a rat. I told Crookes, and on Saturday morning when Harley, 

 Shields and I were looking at the spectrum in the dark room a 

 telegram came from Crookes. He had sent a copy here 1 and I 

 enclose that copy. You may wonder what it means. Helium is 

 the name given to a line in the solar spectrum, known to belong 

 to an element, but that element has hitherto been unknown on 



1 12 Arundel Gardens, their home. 



