Berzelius on Mr. Proufs theory of Atomic Weights. 369 



Art. XIV. — On the hypothesis of Mr. Prout, with regard to 

 Atomic Weights; — in a letter from Berzelius, dated Stock- 

 holm, Dec. 6, 1844. 



Remark. — The following is the translation of a letter receiv- 

 ed from Berzelius, in reply to a request from the Junior Editor of 

 this Journal, that he would favor its pages with an expression of 

 his views on this much mooted question. The reader cannot fail 

 to admire the candor of the distinguished author, and at the same 

 time must admit the justness of his views. — Eds. 



In scientific questions, errors are avoided only by making ex- 

 periment the basis of opinions. Mr. Prout, in bringing forward 

 his views, based them, on the contrary, upon a presumed inaccu- 

 racy in experiments made for determining atomic weights. It 

 seemed to him convenient and advantageous to science, that the 

 atomic weights should be expressed by small numbers, and with- 

 out fractions, and as the weight of hydrogen was relatively much 

 below the others, he proposed to secure this simplicity by consid- 

 ering all a multiple of the atomic weight of hydrogen ; and in 

 carrying out these views, he found that it required but a small 

 change of the ascertained weights, not greater than was deemed 

 unavoidable errors in analyses. 



The basis of Mr. Front's hypothesis, then, is the supposed in- 

 exactness of experiment. The seeming correspondence with it 

 which oxygen and carbon afforded, was thought to authorize a 

 correction of the other atomic weights, so as to make them ac- 

 cord with his hypothesis, although but a mere hypothesis, not ver- 

 ified by observations in the great majority of instances. 



Mr. Prout has given no explanation of the supposed fact on 

 which his theory is based. Such a result could hardly proceed 

 from any thing but the existence of only a single ponderable ele- 

 ment — hydrogen — of atoms of which combined, the compound 

 molecules of all the other so-called elements must consist — each 

 of some definite number. In such a case, whatever be the at- 

 traction uniting the atoms in their compound molecules, we 

 might have expected that in the course of the 1300 years since 

 the alchy mists commenced their experiment, or under the more 



