$.36 METALLURGY*. 



it. We fiiul afterwards that a manufactory liud bneu established 

 at Bristol, where zinc is said to be obtained by distillation per 

 descensum. We have already seen that it had been before ob- 

 tained in Sweden by distillation per uscensuni, which afterwards 

 was effected in larger quantity by Mess. Cronstedt and Rinian, 

 two very celebrated mineralogists and metallurgists. The diih'cul- 

 ties occasioned by the volatile and combustible nature of this metal, 

 fur a long time retarded the knowledge of the ores containing it: 

 nor is that wonderful; as, being of a metallic form, it has even 

 to our times been considered as composed of two or three ingre. 

 dients. Albertus Magnus thinks iron an ingredient ; Paracelsus 

 called it a spurious son of copper ; Lemery holds it to be a species 

 of bismuth ; Glauber, and many alchemists, consider it merely as 

 an immature solar sulphur; Homberg, as a mixture of tin and 

 iron; Kunckel as a coagulated mercury; Schluter, as tin made 

 brittle by sulphur, &c. The celebrated Brandt, in 1?35, shewed 

 that blende contained zinc*; and soon after D. Swab actually ex- 

 tracted it from the Bologtiian pseudo-galena, which possesses a me- 

 tallic splendor. The Baron Punch, in 1714, determined the presence 

 of zinc in pseudo-galena from the flame and the flowerst; and in 

 1/40', Mr. Marggraf set the matter out of doubt. 



Bergman in his history of the discovery of the method of ex. 

 tracting zinc from calamine, wholly omits the mention of Dr. Isaac 

 Lawson ; of whom Pott, in his Essay on zinc, speks very respect, 

 fully, acquainting us that he really obtained some grains of that 

 semi.inetal from calamine. So that though Henckel was the first, 

 Lawson was, probably, the second person in Europe who pro. 

 cured zinc from calamine; whether he was the Englishman who, 

 according to Bergman, went to China to discover the method of 

 doing it, is what I have not been able to learn with certainty. 

 Our English writers, who have touched on this subject, speak in 

 high terms of Lawson, I suppose from their personal knowledge 

 of him, for they do not refer to any written account . Thus 



* Act. Upsal. 



+ Act. Stock. 



f Pott gives us several quotations from a dissertation of Dr. Lavrson's D 

 Nihil, which I have never met with, and amongst others the following one : 

 Qnamvis lapi- caliminaris ncc suliliinationo, lice cum iiuxu ni^ro dct zinctun, 

 taroen >imi! mills in igne color, similis tinctura cupri, el augment uiu 



ponderis probabili .-iinum pnrhcnt argumcfltum lapidem calami iiarem ettc mi- 

 ncram zinci. Pott De Zinco, p. 9. 



