1908] on Davy's Discovery of the Metals of the Alkalis. 11 



tion that these great discoveries have been made within its walls — in 

 that laboratory, and bj those instruments which, from the zeal of 

 promoting useful knowledge, have, with so much propriety, been 

 placed at the disposal and for the use of its most excellent professor of 

 chemistry." 



And now, in the few minutes that remain to me, let me indicate 

 what has been the outcome of this great and fundamental discovery. 

 How far has the expectation of future important results been 

 realised ? Have sodium and potassium at all justified the hope that 

 they would facilitate the means of procuring the comforts and 

 conveniences of life ? 



I have not the time, even if I had the intention, to attempt to 

 follow the many changes in the metallurgy of the metals of the 

 alkalis of the past century. Let me at once proceed to slQw how 

 the matter stands at the end of a hundred years. 



The general properties and chemical activities of potassium and 

 sodium are so very similar that as a matter of commercial production 

 that metal which can be most economically obtained is necessarily the 

 one most largely manufactured, and of the two that metal is sodium. 

 To-day, sodium is made by thousands of tons, and by a process which 

 in principle is identical with that by which it was first made by Davy, 

 i.e. by the electrolysis of fused caustic soda. It is very significant 

 that after a series of revolutions in its manufacture, sodium, having 

 been produced from time to time on a manufacturing scale by a 

 variety of metallurgical methods involving purely thermal processes 

 of reduction and distillation, entirely dissociated from electricity, we 

 should have now got back to the very principle of the process which 

 first brought the metal to light. And that this has been industrially 

 possible is entirely owing to another of Davy's discoveries — possibly 

 indeed tlie greatest of them all— Michael Faraday. As we all 

 gratefully acknowledge, it is to the genius and labours of Faraday — 

 Davy's successor in this place — that the astonishing development of 

 the application of electrical energy which characterises this age has 

 taken its rise. 



The modern method of production of sodium is based, therefore, 

 as regards principles upon the conjoint labours of Davy and Faraday. 



These principles took their present form of application at the 

 hands of a remarkably talented American — Mr. Hamilton Y. Castner 

 — ^ whose too early death, in the full vigour of his intellectual powers, 

 was an incalculable loss to metallurgical chemistry. It is by Castner's 

 process that all the sodium of to-day is manufactured. 



In the Castner process melted caustic soda produced by the 

 electrolysis of a solution of common salt by a metliod also devised by 

 Castner, is brought into an iron vessel shaped like a large cauldron, 

 mounted in brickwork, and provided with an extension adapted to 

 receive the negative electrode. Suspended directly above the cathode 

 is an iron vessel attached to a lid ; to its lower edge is secured iron 



