586 KEPOKT— 1891. 



of chemistry is based. We have also the testimony of the German metallurgist, 

 Becher, who improved our tin-smelting' in Cornwall, He is said to have caused 

 a medal to be struck in 1675, which bore tlie legend : ' Hanc uuciam argenti 

 finissimi ex plumbo arte alchymica transmutavi/ though he should have been aware 

 that he had only extracted the precious metal from the lead, and had not trans- 

 muted the base one. This is a lapse which must be forgiven him, for his terra 

 pinguis was the basis of tlie theory of Phlogiston, which exerted so profound an 

 influence for a century after his death, and he wrote, ' I wist that I have got hold 

 of my pitcher by the right handle, for the pseudo-chemists seek gold, but I have 

 the true philosophy, science, which is more precious.' 



At this critical period what was Boyle doing when the theory of Phlogiston 

 dawned in the mind of the metallurgist Becher ? In 1672 JBoyle wrote his 

 paper on ' Fire and flame weighed in the balance,' and came to the conclusion that 

 the ' ponderous parts of flame ' could pass through glass to get at melted lead con- 

 tained in a closed vessel. It has been considered strange that he did not interpret 

 the experiment correctly, but he, like the phlogistic chemists, tried to show that 

 the subtiUs i(jnis, the material of fire or phlogiston, would penetrate aU things, 

 and could be gained or lost by them. Moreover, his later experiments showed him 

 that glass was powerless to screen u'on from the ' efliuvium of a loadstone.' His 

 experiment with lead heated in a closed glass vessel was a fundamental one, to 

 which his mind would naturally revert if he could come back now and review the 

 present state of our knowledge in the light of the investigations which have been 

 made in the two centuries that have passed since his own work ceased. If he 

 turned to the end of the first century after his death he would see that the failure 

 to appreciate the work of predecessors was as prevalent in the eighteenth century as 

 in the sixteenth. The spirit of intolerance which led Paracelsus to publicly burn, 

 in his inaugural lecture at Basle, the works of Galen, ?Iippocrates, and Avicenna, 

 survived in the eighteenth century when Madame Lavoisier burnt the works of 

 Stahl, but it was reserved for the nineteenth century to reverently gather the ashes, 

 recognising that when the writers of the School of Becher spoke of Phlogiston 

 they meant what we understand by potential energy. 



If Boyle, finding that the Fellows of the Royal Society had not carried out 

 their intention to l)uild a ' Repository and Laboratory,' sought tlie School of Mines 

 and came to the Royal College of Science he would surely thank my colleague. 

 Professor Thorpe, for his vigorous defence last year, as President of this Section, 

 of the originality of the work of Priestley and Cavendish, to which Boyle's own 

 researches had directly led. "\Ve on our part, remembering Berzelius's view that 

 ' oxygen is the centre point round wliich chemistry revolves,' would hope to interest 

 him most by selecting the experiments which arose out of the old metallurgical 

 operation of separating the precious metals from lead by ' cupellation.' When, in 

 conducting this operation, lead is heated in the presence of air it becomes converted 

 into a very fluid dross. Boyle had, in 1661, taken this operation as the very first 

 illustration in his ' Sceptical Chemist ' in proof of his argument as to tlie elemental 

 nature of metals. He would remember the quantitative work of Geber in the 

 eighth century, who stated that the lead so heated in air acquired a ' new weight,' 

 and he would appreciate the constant reference to the ojieration of cupellation from 

 the close of the sixth century B.C., when tlie prophet Jeremiah wrote, to the work 

 of Jean Rey in 1629, whose conclusions he would wish he had examined more 

 closely. Lord Brouncker, as first President of the Royal Society, had called atten- 

 tion to the increase in weight of the lead in the ' coppels ' in the Assay Oflice in the 

 Mint in the Tower, and Slayo had shown that the increase in weight comes from a 

 distinct 'spiritus' in the air. Boyle would incidentally see that Newton had 

 accepted office in the Mint, where he doubtless continued his experiments on cal- 

 cination begun some time before, and, as if to mark his interest in the operation of 

 assaying, figures are represented on a bas-relief on his tomb in Westminster Abbey 

 as conducting cupellation in a muffle. The old work merges wonderfully into 

 the new. Chevreul, in the nineteenth century, confirms Otto Tachen's view in the 

 seventeenth, as to the saponifying action of litharge. Deville employs molten 

 litharge to absorb oxygen dissociated from its compounds, and Graham, by extract- 



