AN UI^DISOOVEREB GAS. 



By Prof. William Ramsay, Ph. D., LL. D., Sc. D., F. E. S. 



A sectional address to members of the British association falls under 

 one of tbree heads. It may be historical, or actual, or i^rophetic; it 

 may refer to the past, the present, or the future. In many cases, 

 indeed in all, this classification overlaps. Your former presidents have 

 given sometimes an historical introduction, followed by an account of 

 the actual state of some branch of our science, and, though rarely, con- 

 cluding with prophetic remarks. To those who have an affection for 

 the past the historical side appeals forcibly; to the practical ihan, and 

 to tlie investigator engaged in research, the actual, perhaps, presents 

 more charm; while to the general public, to whom novelty is often more 

 of an attraction than truth, the prophetic aspect excites most interest. 

 In this address I must endeavor to tickle all palates; and perhaps I 

 may be excused if I take this opportunity of indulging in the dangerous 

 luxury of prophecy, a luxury which the managers of scientific journals 

 do not often permit their readers to taste. 



The subject of my remarks to day is a new gas. I shall describe to 

 you later its curious properties; but it would be unfair not to put you 

 at once in possession of the knowledge of its most remarkable prop- 

 erty — it has not yet been discovered. As it is still unborn, it has not 

 yet been named. The naming of a new element is no easy matter, 

 for there are only twenty-six letters in our alphabet, and there are 

 already over seventy elements. To select a name expressible by a 

 symbol which has not already been claimed for one of the known ele- 

 ments is difficult, and the difficulty is enhanced when it is at the same 

 time required to select a name which shall be descriptive of the prop- 

 erties (or want of properties) of the element. 



It is now my task to bring before you the evidence for the existence 

 of this undiscovered element. 



It was noticed by Dobereiner, as long ago as 1817, that certain ele- 

 ments could be arranged in groups of three. The choice of the elements 

 selected to form these triads was made on account of their analogous 



' Address to the chemical section of the British Association for the Advancement 

 of Science by Prof. William Ramsay, Ph. D., LL.D., Sc. D., F. E. S., president of the 

 section, Toronto, 1897. From Report of the British Association, 1897. 



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