MODERN SCIENCE. 179 



detected, studied, and pointed out the strange adaptations 

 of the local snails and beetles a series of observations 

 which were duly weighed and made use of by evolutionists. 

 This scientist, as we shall see further, was also a physicist of 

 distinction. 



1766 1844. Dalton propounded the ATOMIC THEORY 

 (1808), demonstrating the doctrine held by Leucippus and 

 Democritus (400 B.C.), who, by that marvellous prescience 

 frequently found among the Greeks, had guessed one of 

 the profoundest secrets of nature. Dalton's discovery of the 

 structure of bodies by atoms caused a revolution in the views 

 held hitherto regarding the composition of the universe. It 

 also caused rapid advance in chemistry and science generally, 

 and it is not too much to say that it entitles its author 

 to be called the NEWTON OF CHEMISTRY despite his 

 occasional inaccuracy as an experimenter. The atomic 

 theory rests on three laws which form the foundation of 

 chemical science : (I.) the law of definite proportions i.e., 

 different chemical elements always combine in definite and 

 invariable proportions : thus water will always contain 2 

 parts by weight of hydrogen to 16 parts by weight of 

 oxygen; every carbonate of lime contains 56 parts of lime 

 and 44 of carbonic acid, each of these being likewise as 

 unalterable in their composition as water lime containing 

 71*43 per cent, of calcium and 28^57 P er cen t. of oxygen, 

 whilst carbonic acid contains 27*28 of carbon and 7272 of 

 oxygen ; (n.) the law of multiple proportions, in virtue of 

 which the proportion of one element, having its own weight 

 (atomic), remains constant in forming compounds, whilst 

 the proportion of the other element is a constantly increasing 

 multiple of its weight (atomic) : for instance, nitrogen and 

 oxygen will combine to form five chemical compounds 



So that oxygen enters into composition with other elements 



N 2 



