TKANSACTIONS OF SECTION B. 585 



experiment into greater observations, axioms, and aphorisms : these we call the 

 interpreters of nature.' There are also others 'that bend themselves, lookiug into 

 the experimentsof their fellows and casting about how to draw out of them things 

 of use and practice for man's life and knowledge . . . these we call the doicry men 

 or benefactors.'' In reviewing the history of metallurgy, especially in our islands,, 

 it would seem that the two classes of workers, the interpreters of nature and 

 the practical men, have for centuries sat in joint committee, and, by bringing 

 theoretical speculation into close connection with hard industrial facts, have- 

 ' carried us nearer the essence of truth.' 



The main theme of this address will therefore be the relation between theory- 

 and practice in metallurgy with special reference to the indebtedness of the 

 practical man to the scientific investigator. 



We will then consider — 



(1) Certain facts connected with ' Oxidation ' and ' Eeduction,' upon which 



depend operations of special importance to the metallurgist. 



(2) The influence in metallurgical practice of reactions which are either 



limited or reversible, 

 (•j) The means by which progress in the metallurgic art may be effected^ 

 and the special need for studying the molecular constitution of metals 

 and alloys. 



(1) The present year is a memorable one for chemists, being the centenary ot 

 the birth of Faraday and the bi-cenlenary of the death of Rolert Boyle. The 

 work of the former has recently been lovingly and fittingly dealt with in the 

 Royal Institution, where he laboured so long. I would, in turn, briefly recall 

 the services of Boyle, not, however, on account of the coincidence of date, but 

 because with him a new era in chemistry began. He knew too much about the 

 marvellous action of 'traces' of elements on masses of metal to feel justified 

 in pronoimcing absolutely against the possibilities of transmutation, but he did 

 splendid service by sweeping away the firm belief that metals consist of sulphur, 

 salt, and mercury, and by giving us the definition of an element. He recognised 

 the _ preponderating influence of metallurgy in the early history of science, and 

 quaintly tells us that ' those addicted to chemistry have scarce any views but to 

 the preparation of medicines or to the improvement of metals,' a statement which 

 was perfectly correct, for chemistry was built up on a tlierapeutic as well as a 

 metallurgic basis. The fact is, however, that neither the preparation of materials 

 to be employed in healing, nor the study of their action, had anything like the 

 influence on the growth of theoretical chemistry which was exerted by a few 

 simple metallurgical processes. Again, strange as it may seem, theoretical 

 chemistry was more directly advanced by observations made in connection with 

 methods of purifying the precious metals, and by the recognition of the quantitative 

 significance of the results, than by the acquisition of facts incidentally gathered in 

 the search for a transmuting agent. The belief that chemistry ' grew out of 

 alchemy ' nevertheless prevails, and has found expression in this Section of the 

 British Association. As a fact, however, the great metallurgists treated the search 

 for a transmuting agent with contempt, and taught the necessity of ' investigation 

 for its own sake. George Agricola, the most distinguished of the" sixteenth-century 

 metallurgists, in his work ' De Ortu et Causis Subterraneorum ' (lib. v.), written 

 about the year 1539, disdainfully rejects both the view of the alchemists that 

 metals consist of sulphur and mercury, and their pretended ability to change silver 

 into gold by the addition of foreign matter. 



Biringuccio (1540) says, ' I am one of those who ignore the art of the alchemists 

 entirely. They mock nature when tliey say that with their medicines they correct 

 its delects, and render imperfect metals perfect.' 'The art,' he adds, 'was not 

 worthy of tlie consideration of the wise ancients who strove to obtain possible 

 things.' In his time, reaction between elements meant their destruction and re- 

 constitution, nevertheless his sentence ' transmutation is impossible, because in order 

 to transmute a body you must begin by destroying it altogether,' suggests that 

 he realised the great principle of the conservation of mass upon which the science 



