402 SCIENTIFIC THOUGHT. 



as a kind of revelation, and it is not surprising that it 

 came late in the course of civilisation. 1 



Nothing can have tended more in this direction than 

 the success of the Newtonian gravitation formula, and of 

 the simple laws of motion, which, at the time of the birth 

 of modern chemistry, stood firmly established as the key 

 to all problems of physical astronomy. No wonder that 

 men were on the look-out for correspondingly simple 

 perhaps analogous relations in the world of molecular 

 phenomena. One of the earliest suggestions, which came 

 forward soon after Dalton's atomic view had helped to 

 establish the prevailing rule of fixed and of multiple pro- 

 portions in the chemical combinations and reactions of 

 matter, was the idea that, as to each element belonged a 

 definite combining number, all these numbers must be the 

 multiple of the lowest among them, the equivalent or 

 is. atomic weight of hydrogen. This is Prout's celebrated 

 hypothesis, hypothesis, which had some ardent admirers, and which 

 has been repeatedly abandoned and revived in the course 

 of this century. 2 It is hardly possible to maintain it any 

 longer, since the accurate and elaborate measurements of 



1 Except indeed the Pythagorean 

 notions are regarded as an anticipa- 

 tion of it. 



2 The hypothesis of Prout, pub- 

 lished anonymously in 1815, and 

 warmly defended by Thomson, has 

 been again and again revived. From 

 the beginning it was put forward 

 together with the suggestion that 

 the different elementary substances 

 might after all turn out to be all 

 derived from one and the same 

 primary form of matter, and that 

 the atoms of this might in the 

 atoms of our present elements 

 merely be aggregated in different 

 numbers and figures, held together 

 by forces, which by the means and 



processes at our command could 

 not be broken up. This primary 

 substance might then be either 

 hydrogen, the lightest in weight of 

 known substances, or some other 

 substance of which hydrogen itself 

 was an atomic multiple. Abroad, 

 Prout's hypothesis was disproved 

 by Berzelius's accurate determina- 

 tions, in England by Turner's, and 

 about 1830 it fell into oblivion. It 

 was again revived in 1840 by Dumas, 

 who, as well as his followers, Lau- 

 rent and Gerhardt, favoured the 

 idea that the explanation of the 

 different properties of chemical com- 

 pounds, notably organic compounds, 

 was to be found in the arrangement 



