Translation of "Key's Essai/s. 73 



printed with notes, by M. Gobet, at Paris, and published by Ruault, Rue- 

 de-la-Harpe, The copies of this reprint disappeared in a verj' sudden and 

 remarkable manner, and the work was so little known in this country, 

 that Doctor James Curry, at the sale of whose library, in 1 820, I pur- 

 chased a copy of it, states in a note at the beginning of the work, appa- 

 rently in his own hand-writing, that he had sought it, in vain, for more 

 than ten years, in every bookseller's catalogue in London, till, at last, the 

 present copy rewarded his trouble, and he adds, that he had seen but one 

 other copy since. The suppression of this edition, almost immediately 

 after its publication, which took place in about three years from the pro- 

 mulgation of Lavoisier's first experiments * would naturally lead to the 

 suspicion, that it was effected by that celebrated philosopher or his friends, 

 to avoid the imputation of plagiarism, which might sully the brilliancy of 

 his recent discoveries, and this imputation is, in the opinion of many, but 

 too probable. Mr. Brande, however, has given an interesting note in his 

 Dissertation on the Progress of Chemical Philosophy, prefixed to the third 

 volume of the Supplement to the 4th and 5th editions of the Encyclopaedia 

 Britannica, containing a quotation from two scarce volumes of the 

 posthumous works of Lavoisier, in Mr. Hatchett's library, in which La- 

 voisier expressly states, that he knew nothing oi Key's, Essays, when, in 

 1772, he undertook a series of experiments on the different kinds of air 

 or gas, disengaged during effervescence, and in many chemical opera- 

 tions ; whence he learnt the true cause of the increase of weight, which 

 metals acquire by the action of firef . At the end of that note, he further 

 states a precaution he had taken in November, 1773, to secure to himself 

 the sole merit of the new French theory, claiming it exclusively for his 

 own. It would be uucourteous, were that celebrated philosopher still 

 living, and ungenerous now he is dead,' to question the truth of his 

 assertion ; nor do I conceive I have any more right than I have inclination, 

 to do so. His ignorance of Key's work is, perhaps, not veiy extraor- 

 dinary, since, as will appear by M. Bayeu's letter, at the end of the 

 Avertissement, that the book was extremely rare, and probably known to 

 very few. After the publication of that letter, however, in 1775, Lavoi- 

 sier must have known, and have read Rey's Essays, as, indeed, appears 

 from his own words in the note already quoted ; and, it is matter of 



• Read at the Academy of Sciences at Paris, November 12th, 1774, 

 and published in the Journal de Physique, Vol. IV. p. 448. 



f " J'ignorois alors ce que Jean Rey, avoit ^crit ;\ ce sujet in 1630, et 

 quand je I'aurois connu, je n'aurois pu regarder son opinion a cet ^gard, 

 que comme une assertion vague, propre a. faire honeur au g^nie de 

 I'auteur, mais qui ne dispensait pas les chimistes de constater la v<;rit6 de 

 ton opinion par des experiences." 



