1908] on Davy's Discovery of the Metals of the Alkalis. 9 



" Should the bases of potash and soda be called metals ? The 

 greater number of philosophical persons," he says, "to whom this 

 question has been put, have answered in the affirmative. They agree 

 with metals in opacity, lustre, malleability, conducting powers as to 

 heat and electricity, and in their qualities of chemical combination. 



" Their low specific gravity does not appear a sufficient reason for 

 making them a new class ; for amongst the metals themselves there 

 are remarkable diiferences in this respect. ... In the philosophical 

 division of the classes of bodies, the analogy between the greater 

 number of properties must always be the foundation of arrangement. 



" On this idea, in naming the bases of potash and soda, it will be 

 proper to adopt the termination which by common consent has been 

 applied to other newly discovered metals, and which, though originally 

 Latin, is now naturalised in our language. 



" Potasium {sic) and sodium are the names by which I have ven- 

 tured to call the new substances ; and whatever changes of theory, 

 with regard to the composition of bodies, may hereafter take place, 

 these terms can scarcely express an error ; for they may be considered 

 as implying simply the metals produced from potash and soda. I 

 have consulted with many of the most eminent scientific persons in 

 this country upon the methods of derivation, and the one I have 

 adopted has been the one most generally approved. It is perhaps 

 more significant than elegant. But it was not possible to found 

 names upon specific properties not common to both ; and though a 

 name for the basis of soda might have been borrowed from the Greek, 

 yet an analogous one could not have been applied to that of potash, 

 for the ancients do not seem to have distinguished between the two 

 alkalies." 



Such, then, are the more significant features of one of the greatest 

 discoveries ever made l)y a British chemist, as these are set forth in 

 one of the most remarkable papers in the Philosophical Transactions 

 of the Royal Society. 



Sir James Dewar has been so good as to have prepared for me 

 a photographic reproduction of a water-colour drawing of tiie 

 labonitory of the Royal Institution as it existed in Davy's time, 

 showing the actual spot where the isolation of the metals of the 

 alkalis was first effected. 



The publication of Davy's discovery created an extraordinary 

 sensation throughout the civilised world, a sensation not less pro- 

 found, and certainly more general from its very nature, than that 

 which attended his lecture of the previous year. But at the very 

 moment of his triumph, it seemed that the noise of the universal 

 acclaim with which it was received was not to reach him. I have 

 already made reference to the condition of mental excitement under 

 which the discovery was made and prosecuted. Almost immediately 

 after the delivery of his lecture he collapsed, struck down by an ill- 

 ness which nearly proved fatal, and for weeks his life hung on a 



