504 INDUCTION. 



a small portion of what he considered as magnesia 

 present in a mineral he had analyzed. It is on this 

 principle, too, that the small concentrated residues of 

 great operations in the arts are almost sure to be the 

 lurking places of new chemical ingredients : witness 

 iodine, brome, selenium, and the new metals accom- 

 panying platina in the experiments of Wollaston and 

 Tennant. It was a happy thought of Glauber to 

 examine what everybody else threw away*." 



The disturbing effects mutually produced by the 

 earth and planets upon each other's motions were 

 first brought to light as residual phenomena, by the 

 difference which appeared between the observed places 

 of those bodies, and the places calculated on a con- 

 sideration solely of their gravitation towards the sun. 

 It was this which determined philosophers to consider 

 the law of gravitation as obtaining between all bodies 

 whatever, and therefore between all particles of matter; 

 their first tendency having been to regard it as a force 

 acting only between each planet or satellite and the 

 central body to whose system it belonged. Again, the 

 catastrophists, in geology, be their opinion right or 

 wrong, support it upon the plea, that after the effect 

 of all causes now in operation has been allowed for, 

 there remains in the existing constitution of the earth 

 a large residue of facts, proving the existence at 

 former periods either of other forces, or of the same 

 forces in a much greater degree of intensity. To add 

 one more example : if it be possible to establish, what 

 is generally rather assumed than proved, that there is 

 in one human individual, one sex, or one race of 

 mankind over another, an inherent and inexplicable 

 superiority in mental faculties, this must be proved 



HERSCHEL, ut supra, pp. 156-8, and 171. 



