Translation of Rey's Essaj/s. 139 



common lead*, when calcined, gains eight or ten per cent, in 

 weight. Then, seeking for the cause, he says it is the soot por- 

 duced by the fire, which striking against the vault of the rever- 

 beratory furnace, falls back on the matter, which Csesalpin 

 would never have advanced, if he had paid attention to what I 

 am about to remark. First, the soot, as it is gradually exhaled 

 by the fire, is of so thin a nature that the seven ounces of in- 

 crease found by the Sieur Brun, would occupy more space than 

 all the calx he derived from hi* calcination. In the second 

 place, the abundance of soot would so blacken the calx of tin 

 and of lead, that the ladies would never whiten their faces with 

 it, as many do. Besides, what should hinder us from increasing 

 the calx ad infinitum, since the fire may be kept up as long as 

 we will, and would always furnish soot ? Let me add, that the 

 Sieur Brun calcined his tin with a naked open fire, so that the 

 soot could only pass on one side, by the registers of the fur- 

 naces, and fly off, and not fall down on the substance, in which 

 too it could not sink, being lighter than the air contained in the 

 vessel. As to Libavius, he rejects the opinion of Csesalpin, 

 and even says that the very apprentices in chemistry will 

 laugh at it, without, however, having himself adduced much by 

 way of argument against it, (« Vencontre,) wrapping up his opi- 

 nion in such a heap of words, that it is not easy to develope it. 

 Yethe wouldhave such expressions as these be received as a so- 

 lution of the difficulty. " Transmutation changes the weight," 

 and a few lines further, " Burning increases the weight of the 

 lead." The better to see the force of which answers, we need 

 only slightly vary the terms of our question, (the sense re- 

 maining the same,) and apply them to him as thus. Why does 

 the transmutation of lead into calx alter its weight? Because, 



*Piomb noir, so translated by Cottgrave. The mineral called black lead, 

 plumbago, (carburet of iron,) seems to have been called jdumbagine, 

 which Cottgrave says " is pure lead, turned almost into ashes by the ve- 

 hemence of the fire. This is the artificial idonibagiue, and cumes of lead 

 put into the furnace with gold or silver ore, to make them melt the sooner 

 (by which employment it gains some part in the worth of those metals.) 

 There is also a natural or iniucial plombagine, which (as MatliioUiH 

 thinkeih,) is no uiiitr lluin bilvcr mingled wiih Icad-btoiit, or ore." 



