10 Biographical Memoir qf'M, Duhamel. 



as the founderies of carron and iron balls at Lanoue, and pub- 

 lished, as we have already mentioned, his secret with respect 

 to the cementation of steel. 



In 1779, he projected great improvements in the refining of 

 silver, that is to say in the art of separating that metal from 

 copper by means of lead. In 1783, he invented an instrument 

 calculated fcr following better the direction of veins, and for 

 determining the points at which they cross. In 1 784 especially, 

 the period of a great competition for a place in the Academy, 

 he presented still more numerous memoirs than formerly. He 

 furnished a means of extracting metal from the poorest galenas ; 

 taught how to treat without loss the ores rich in iron, by add- 

 ing to them in suitable proportions earths calculated to produce 

 a sufficient laitier, and thus prevent their combustion ; shewed 

 that most of the scoriae of lead may still be turned to account ; 

 and pointed out the surest means of extracting gold and silver 

 from goldsmith's ashes. 



These last works procured him successively in the Academy 

 the places of correspondent and associate, and at length obtained 

 for him from the government the recompense so long promised 

 to his first efforts. 



The minister of Louis XVI. resumed the old projects of M. 

 Trudaine. In 1781, M. Necker laid the first foundation of 

 their realization, and, in 1783, M. de Calonne completed it. A 

 school of mines was established at Paris, and after more than 

 twenty years expectation, M. Duhamel was nominated to the 

 chair of mining and metallurgy. 



Undertaking such an office was devoting himself somewhat 

 late to an occupation for which he was designed from his youth, 

 and which should have been commenced with the active vigour 

 of that age. Not only was it difficult for M. Duhamel to ac- 

 quire all of a sudden the elocution which could alone fix the at- 

 tention of his pupils ; he had also to learn in detail the theories 

 whose progress the exercise of art, and a life passed in forges 

 and manufactories had not permitted him to follow, and to en- 

 ter anew upon the meditations necessary for arranging them so 

 as that they might be brought forward in a manner worthy of 

 his office. He had to inform himself in short of all that science 



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