280 ON MR. dalton's principle of combination. 



VI. 



Remarks on Mr, D Alton's HypoihesU of the manner in 

 which Bodies combine ivith each other. In a Letter from 

 John Rostock, M.D. 



To Mr. NICHOLSON. 

 SIR, 



.N the first part of Mr. I)alton*s system of chemical philo- 

 K^v principle soph}', he announced the existence of a new principle, ve- 

 " ^* specting the manner in which bodies combine with each 

 other. At the time he went no farther, than merely to state 

 the outline of his hypothesis, refering to the subsequent 

 part of his work, for the fiicts and ex[)erinients from which 

 it was derived. The second part of the system being now 

 published, and a considerable portion of it being occupied 

 with details, which may be considered as dependant upon,, 

 or illustrative of the hypothesis, and the truth of it being 

 assumed as the foundation of a great part of Mr. Daltou's 

 reasoning, we may be fairly entitled to enter into an exami- 

 nation pf the proofs, which are adduced in its support. 

 In order to assist us in forming a clear conception of the 



Different gubiect, it may be desirable to refer to the different ways 



modes of es« . *^, . , •' , ,. , , ,, . , * 



tablishinga m which we attempt to establish a new hypothesis. We 



new hypothe- m^y show, that it is consonant to the generally received laws 

 of physics, that it coincides with previously admitted facts, 

 and is deducib^e from them ; or, proceeding without these 

 previous steps, we may propose a ngw opinion, that is un- 

 supported by analogy or induction, and afterwards endea- 

 vour to substantiate it, by experiments an(i^ observations 

 made expressly for that purpose. To the latter of thesethe 

 term hypothesis more strictly applies, while the farmer is 

 more correctly denominated theory \ and as our plan of pro-^- 

 ceeding in the investigation of any truth must be consider- 

 ably different, according as we adopt the ope or the other 

 of these modes, it is of some importance to bear in mind 

 the distinction, which subsists between them. It will, \ 

 think, be found, that Mr. Dalton's doctrine is altogether 

 hypothetical, or one which depends for its proof entirely 

 upon subsequent observations and experiments. By those 



who 



