OQQ ON MR. DALTON*S PRINCIPLE OF COMBINATION. 



be in the ratio of 100 to 136*. With respect to the nitrous 

 oxide, the ratio seems favounible to the hypothesis, for if 

 we suppose, that 100 atoms of oxigen are combined with 

 400 atoms of azote, to produce 100 atoms of nitrous oxide, 

 the proportion of the constituents would be in the ratio of 

 ' 100 to 59» which is very nearly what it appears to be from 

 analysisf. Here, therefore, one case appears to be favour- 

 able, and the other adverse to the hypothesis. 



I shall now re^verse the above calculations, and assume 

 that nitrous oxide is the binary compound, which Mr. Dal- 

 ton supposes to be the case. On this principle the atom of 

 oxigen will be to the atom of azote nearly as 100 to 1/0, or 

 as 1 to 1*7. The constituents of nitric oxide will then be in 

 the ratio of 100 to 1 17*6, and of nitric acid as 100 to nearly 

 ^33. I have only admitted three compounds of oxigen and 

 azote, because, even although we suppose nitrous acid, and 

 oxinitric acid to be substances that are always uniform iu 

 their composition, q supposition which is at least doubtful, it 

 seems natural even on Mr. Dalton^s hypothesis, to regard 

 them as secondary compounds, formed by the union of a cer- 

 tain number of atoms of nitric acid with a certain number of 

 atoms of azote, in the one case, and of oxi<j^en in the other. 

 The facts do I shall not think it necessary to pursue this cxaminatioo 



the h** mhe- ^^^ farther, the examples which have been adduced are suffi- 

 »!s, cient to establish the conclusion, that although the facts occa- 



sionally coincide with the hypothesis, they more frequently 

 oppose it. it will perhaps be said, that these analyses arc 

 not correct, and I am far from denying that this may be 

 •the case, althouj^h I have purposely selected these, which 

 appear to stand upon the best foundation. But here we 

 must recollect the difference between a theory and an hypo- 

 thesis : had it been shown by a previous train of reasoning, 

 that Mr. Dalton's opinion was supported by any strong 

 analof^Vj or that any poweful arguments could be adduced 

 in its favour, we might then have been permitted to adjust 

 the facts to the theory. As the question now stands, how- 

 ever, we are to prove the hypothesis solely from the facts, 

 and therefore we are not to object to the facts merely be- 



♦ Thomson, II, 168'. f llb\L 



caiise 



