CHAPTER III 



THE BURNING OF METALS AND THE DISCOVERY OF OXYGEN 



A. THE BURNING OF METALS. 



Jean Rey (1630) shows that lead and tin increase in 

 weight when burnt It has been known from very early 

 times that the metals, except gold and silver, are, by heating, 

 gradually changed to powders of various colours. These 

 powders were called CALCES from the resemblance which 

 they showed to lime (Latin, calx), and the process of 

 burning was called CALCINATION. A casual examination 

 showed that the calx was a lighter material than the metal 

 from which it was formed; it was, therefore, natural to suppose 

 that the burning of the metal had resulted in a loss of 

 weight, just as is obviously the case when wood or coal is 

 burnt. The fact "that tin and lead increase in weight 

 when they are calcined," was therefore "observed with 

 astonishment " by those who first put the matter to the test 

 of experiment. 



The Essays of Jean Rey (1630), a French Doctor of 

 Medicine, " On an Enquiry into the cause wherefore Tin 

 and Lead increase in weight on Calcination" (Alembic Club 

 Reprints, No. XI), contain an account of one of the earliest 

 chemical researches of which a clear record has been pre- 

 served. He records that Brun, an apothecary of Bergerac, 



" having placed two pounds six ounces of fine English tin 



in an iron vessel and heated it strongly on an open furnace 



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