1812. &T. 34.] PROFESSOR DAVY. 375 



' Had Mr. Berthollet obtained oxygen from chlorine 

 there would have been no error in his theory, but by 

 not attending to the minute circumstances of his 

 experiment, by not ascertaining that the water present 

 acted no part and was not decomposed, he fell into an 

 error, and of course all the conclusions he drew were 

 false and erroneous. Nothing should be allowed but 

 what can be proved by experiment, and nothing should 

 be taken for granted upon analogy or supposition.' 



Faraday concludes this lecture thus : - Mr. Davy now 

 proceeded to comment and make observations on the 

 former theory of chlorine gas. Here I was unable to 

 follow him. The plan which I pursue in taking of 

 notes is convenient and sufficient with respect to the 

 theoretical and also the practical part of the lecture, 

 but for the embellishments and ornaments of it it will 

 not answer. Mr. Davy's language at those times is so 

 superior (and indeed throughout the whole course of 

 the lecture) that then I am infinitely below him and 

 am incapable of following him even in an humble 

 style. Therefore I shall not attempt it; it will be 

 sufficient to give a kind of contents of it. 



6 He said that hypotheses should not be considered as 

 facts and built upon accordingly. Nevertheless, if 

 cautiously pursued, they might lead to mature fruit. 

 That nothing should be taken for granted unless proved. 

 By considering oxygen as contained in chlorine the 

 whole chemical world had been wrapped in error 

 respecting that body for more than one-third of a 

 century. 



6 He noticed that all the truly great scientific men 



