76 Tramhtion o/" Key's Essai/s 



" M. Spielman, professor of chemistry, at Strasbourg, recom- 

 mends the Essays of John Rey to students, in the edition of his 

 " Institutions de Chimie " of 1766, also translated into French. 

 M. de Bordeu, in his " Recherches sur les Maladies Chroniques, " 

 No. 93, octavo, one volume, makes so honourable mention of 

 John Rey, that we invite the curious to have recourse to it. — 

 M. Jean Frederick Corvin sustained a thesis, entitled Historia 

 aeris factitii, under the presidency of M. Spielman, at Stras- 

 bourg, on the 4th of December, 1776, a pamphlet of sixty pages 

 in 4to., -with figures, in which John Rey is named as the first 

 author, who has written on this important subject. The ele- 

 ments of chemistry for tlie public course of the academy of 

 Dijon, of this year, may also be consulted. M. Sage praises it 

 in his Mineralogie Docimatique, lately reprinted. Finally, M. 

 Bayen, a celebrated chemist, was the first to do justice to John 

 Rey, and he has permitted his Letter to M. L'Abbe Rozier to be 

 printed at the beginning of this edition." 



A Letter from M. Bayen*, chief Apothecary of the Army, Sfc, 

 to M. L'Abbk' Rozier, Dignitari/ of the Church of Lyons, &c. 



Monsieur, 



The cause of the increased weight that certain metals expe- 

 rience by calcination, has, at all times, been a subject of specu- 

 lation and research with chemists and natural philosophers. 

 Cardan, Caesalpin, Libavius, and many others, formerly endea- 

 voured to explain this phenomenon ; but amongst them all, we 

 must, in justice, distinguish John Rey, a physician of Perigord, 

 who lived at the beginning of the last century. His work, per- 

 haps unknown to all the chemists and naturalists of the present 

 day, appears the more deserving to be rescued from oblivion, 



public " Why sacrifice it ? Could it not have been copied without in- 

 juring the original ? Or, wr.s it in 1777, as more recently, found easiest to 

 print at once from, the lacerated pages of the unfortunate original ? Your 

 own, or whose else, no matter ! 



* Published in the 5th volume of the Journal de P/ii/sique, pari I. 1775. 



