COMPLEXITY OF MATTER. 33 



planets and their satellites.' 1 According to Angstrom 

 and Thalen, pure iron ignited to whiteness simultaneously 

 emits rays of light of more than 460 different rates of 

 vibration ; and titanium emits even a very much larger 

 number. 



Heat or pressure applied to a piece of steel alters its 

 length, breadth, thickness, molecular arrangement, atomic- 

 distance, specific gravity, cohesive power, adhesion to 

 liquids, elasticity, temperature, specific heat, latent heat, 

 thermic conductivity, thermo-electric power, electric-con- 

 duction-resistance, magnetic capacity, chemical and che- 

 mico-electric actions, and a number of other properties 

 simultaneously. In a paper on ' The Molecular Move- 

 ments and Magnetic Changes in Iron at different Tempe- . 

 ratures,' 2 I have remarked, ' The changes produced by 

 heat in even so apparently simple a substance as iron were 

 so numerous in some of the experiments as to produce the 

 impression that the metal was endowed with vitality.' 

 This simultaneous change of properties is a general attri- 

 bute of matter, and iron and the magnetic metals gene- 

 rally are only conspicuous instances of it amongst elemen- 

 tary bodies, probably because they possess the greatest 

 number of molecules in a given space, and have their pro- 

 perties thereby condensed. 



The phenomena of light and sound teach a similar 

 lesson. Although the atmosphere is substantially a mix- 

 ture of only two simple gases, the smallest portion of it is 

 capable of transmitting at the same instant, with but 

 little interference, not only an almost infinite number of 

 rays of light of every different degree of refrangibility, but 

 also millions upon millions of acoustic vibrations emitted 



1 Jevons's Principles of Science, vol. ii. p. 452. 



2 Philosophical Magazine, September, 1870. 



D 



