THE BEGINNINGS OF II FE. 49 



whilst the other acid and base still continue in a state 

 of solution. This is an occurrence of much importance, 

 since it tends to show that chemical affinities which 

 may be held in abeyance at certain temperatures may, 

 at other temperatures, assert themselves, and thus lead 

 to the initiation of molecular .combinations which 

 result in the emergence from the solution of a new kind 

 of solid aggregate. 



We have illustrated our remarks hitherto by a 

 reference to the behaviour of simple saline substances, 

 though all the observations that have been made are 

 equally applicable to chemical substances in general. 

 It is quite immaterial whether we have to do with 

 simple substances or with highly complex bodies: the 

 properties of all alike are dependent upon their mole- 

 cular composition and nature. Molecular composition is 

 an important item even with reference to substances 

 which are looked upon as elementary — different modes 

 of composition or arrangement of the atoms sufficing to 

 produce what are called ^allotropic' states. We are 

 most familiar with these as they are presented to us in 

 the various forms of carbon. The differences between 

 the diamond, graphite, anthracite, and pure charcoal 

 are most striking,* and yet these are all different states 

 of one and the same substance whose ultimate atoms 

 are differently grouped. Oxygen^, sulphur 2, and 



^ Ordinary oxygen, and ozone whose molecule is supposed to be 

 represented by O4. 



2 Sulphur crystallizes in rhombic octahedrons belonging to the 

 VOL. II. E 



