Prei7c/i Nbiional Instiluie. ^Of 



in ay be the consequences to which they lead, whatever are 

 the resuUs ol)taiuecl, provided they be just, the instant ihey 

 asiume a character ot" novelty, t;./y beeonie usetul : everv 

 fact has a deierniinate place, uhich can be held by itself 

 alone, and we ought to consider the edifice of the sciences 

 as that of nature: every thing is infinite, every thing ne- 

 cessary. We may go further: in short, the progress oF 

 truth is not essentially retarded because those who devotQ 

 their talents to philosophical subjects occasionally fall into 

 erroneous roads. The most usciul discoveries have sprung 

 from the greatest errors. Wc find the j)roof of this in the 

 labours which have been undertaken to overturn modern 

 chemistry, and to support the old theory of combustion* 

 'J'he complication of the phjsnomena in this latter science 

 will even I e the cause that the proofs of this description 

 will still continue to be multiplied : facts do not always 

 present themselves imder the same characters; they are 

 {studied under other points of view, they are seen with dif- 

 ferent eyes, and the results' to which they learl are not 

 similar. I'his is precisely the case at present with respect 

 to the discussions which have arisen between Mr. Daw and 

 associates Messrs. Gay Lussac and Thenard. 



CHEMISTRY. 



In former reports we have given an account of the dis- 

 covery of Mr. Davy, as to the changes that potash and soda 

 undergo by the action of the Voltaic pile, and of the pro- 

 cesses by which Messrs. Gay Lussac and Thenard produced 

 these changes without the help of the above instrument. 



Mr. Davy thought that in these experiments the potash 

 and soda were subjected to a deoNygenation, and tliat a 

 true metal resulted from it, which was particularly distin- 

 guished from other substances of this kind by an extreme 

 affinity for oxygen. He called these two nicials potassium 

 and sodium. Messrs. Gay Lussac and Thenard, esta- 

 blished on the contrary, by several experiments, but parti- 

 cularly by the products obtained on analysing the combi- 

 nation of the potassium with ammonia, were of opiihoii 

 that the changes of potash and of soda were owing to a 

 particular combination of these alkalis with hydroo;en» 

 Mr. Davy, having repeated the experiments on whichlhis 

 opinion is founded, has not obtained results conformable to 

 those which had been announced by the French cheniists ; 

 this ha? given rise to sonie observations bv Messrs. Gay 

 Lusfcac and Thenard, in which they show that the dif- 

 ferences found between the results of Mr. Davy's, experi- 



U 2 njcius 



