igeiK 



5f5 ON MR. DALTON's principle OF COMBINATION. 



Compounds of Thomson, to consist of 53 parts of sulphur and 47 of oxi- 

 ulphuraad jten, or 100 parts of sulphur to 88*6 of oxigen*. Now in 

 this case the proportion ofoxigen to the sulphur is dimi- 

 nished, thei-efore the 100 parts of oxigen, which entered into 

 the composition of sulphuric acid, will be combined with 

 a greater number of atoms of sulphur, and the next smallest 

 quantity with which they can unite is the next multiple of 

 100, that is 200. Sulphurous acid will therefore be com- 

 posed of lOOatoms of ox i gen, and 200 'atoms of sulphur. 

 Now supposing the weight of an atom of sulphur to be to 

 an atom of oxigen as 1 to T365, the weight of the two atoms 

 of sulphur in sulphurous acid will be to the single atom of 

 oxigen as 9. to 1*365, netirly as 6 to 4, so that 100 parts of sul- 

 phdroua acid will consist of 60 parts of sulphur and 40 parts 

 t>f oxigen. The third compound of sulphor and oxigen is 

 the oxide of sulphur, and this is stated, upon the same au- 

 thority with the lastf, to be composed of 100 parts of sul- 

 phur with 7 of oxigen. Here as before we are to taVe the 

 oxigfen as the fixed quantity, and to find some multiple of 

 100 which may express the proportion t)f sulphur. Now if 

 we suppose that one atom of oxigen unites with l.Q atoms of 

 sulphor, to form the oxide of sulphur, or that 100 atoms of 

 the oxide of salphur are composed of 100 atoms of oxigen 

 and 1900 atoms of sulphur, we shall find, by following the 

 same method of calculation, that the weight of sul|)bur to 

 that of oxigen will be very nearly as 57 to 4. With respect 

 to sulphur therefore it appears, that one case is favourable 

 to the hypothesis and the other adverse to it; for tlie ana- 

 lysis of the sulphurous acid rrtakes the sulphur to the oxigen 

 as 53 to 47> while the proportion of 57 to 4, for the oxide of 

 sulphur, agrees very nearly with Dr. Thonibon's estimate of 

 100to7+. 



* Thomson, I. 87. f Thomson, I. SS. 



:}; As llje oxide of sulphur has probably a real existence, and as the 

 numbers which D)-. Thomson has assigned fur its constituents coin- 

 cide remarlcably with Mr. Daltou's hypothesis, I have given it a place 

 in the calculation?, although my opinion is, that we have not yet s«f- 

 ficient grounds for forming an exact estimate of the proportion of its 

 elements, and the above coincidence is purely accidental. See Dr. 

 Thomson's paper in Nich. VI, lOl. 



I will 



