416 LIFE OF DALTON: 



We may further remark that even had the labours of 

 Mr. Higgins been known to him, he still must be accounted 

 the Discoverer of the general law of multiple proportions, of 

 their connection with the relative weights of combining atoms, 

 and of many of the methods by which this great principle is 

 verified and made the foundation of practical chemistry. 

 These are the points upon which Dalton's fame will indispu- 

 tably rest with posterity. 



He has himself furnished few materials for marking the 

 successive steps of his research. We are told of Kepler that 

 he tried eighteen hypotheses as to the orbit of Mars, before 

 reaching the discovery of the true one. Dalton was led by 

 the course and results of his earlier labours, to conceive the 

 power of subjecting to numerical forms the endless and 

 seemingly capricious varieties of chemical phenomena. We 

 know not precisely where the light first broke in upon him ; 



where, perchance, it was again obscured for a time by the 

 imperfection of the analyses upon which his doctrine depended ; 



or where, finally, he saw before him the full day of the dis- 

 covery. The main facts appear to be, that he derived his 

 earliest conception of the law of multiple proportions from 

 his experiments on gases, or matter in the aeriform state ; 



that in a paper read to the Manchester Society, Nov. 12, 

 1802, he announced the first example of this law in the com- 

 binations of oxygen and nitrous gas ; that the atomic view 

 of chemical combinations occurred to him in direct sequel to, 

 if not simultaneously with, the establishment of the law ; 

 that in October, 1803, he read another paper to the Society, 

 in which, after stating that he believes the enquiry to be en- 

 tirely new, he assigns the relative atomic weight of twenty- 

 one bodies, gaseous, fluid, and solid ; and that in May, 1808, 

 he published his 'New System of Chemical Philosophy,' 

 embodying these various results of the continuous labour of 

 years. In a letter to his brother Jonathan (March, 1803) 



