ON MB. ©ALTON S PRINCIPLE OF COMBINATION. 



Uidrogen pnd one of oxigen, or in short of any assignable 

 number of atoms of hidrogeu and oxigen? 1 do not ptrceive, 

 that Mr. Dalton has f^iven any reasou jn sujvport of t,his 

 binary combination, in preft^rence to all the rest, and 1 am 

 unable to conjecture what reason can be urgedjn its iavour. 

 If we feel a difficulty in assonting to the iirst of ihes*; rules, 

 still more shall we be inclined to hesitate, as we advance to 

 the more complex cases, wliich are stated m the L>nd, 3d, 

 siud 4th. It is obvious, that as there is more scope for vari- 

 ety in the mode of coinbinatiou, in the same ratio dots the 

 probability of Mr. Dalton's supposition diminish. It is not 

 necessary to enter into the consideration of the other " gene- 

 ral conclusions,'* because the estimates which are formed of 

 the weights of oxigen, hidrogen, and azote, as laid down in 

 the first two, enter as elements into all the subsequent cal- 

 culations. We may therefore conclude this part of the in- 

 quiry by stating, that the positions respecting the weight of 

 the atoms of oxigen, hidrogen, and azote, as luid down in 

 the first part of Mr. Dalton's system, are entirely hypothe- 

 tical, are assumed without any authority either from analo^ry 

 or induction, and that consequently, they must rest entirely 

 upon such facts as the author brings forwards expressly for 

 their support. 



Assuraptions The points which Mr. Dalton has here assumed, and 

 of Mr.Dalt«n. ,vhich remain to be proved, are the following. First, that 

 when only one combination of two elementary bodies can 

 be obtained, it must be binary ; 2nd. That only one com- 

 bination of oxigen and hidrogen, and only one combination 

 of hidrogen and azote can exist; 3d. That the ratios of 1 to 

 7, and of 1 to 5 express the relative weights of these atoms. 

 It may be confidently asserted, that these steps in the proof 

 are so intimately connected together, and that the last de- 

 pends so entirely upon the previous ones, that the least flaw 

 in either of them must utterly demolish the whole hypothe- 

 sis. I shall now turn to the 2nd part of the system, where 

 the author promised that the facts and experiments should be 

 Elementary detailed, from which the conclusions were derived. The 

 principle*. fir^t chapter is on ** elementary principles," oxigen, hidro- 

 gen, azote, &c, ; each of these individually forms the sub«? 

 ject of a short section, in which the mode of procuring them 



is 



