2i2 PHYSICAL BASIS OF CIVILIZATION 



The element carbon plays an important part in 

 the composition of living substance. In atomic 

 weight it stands close to the three elements just 

 mentioned. It differs from them in being a solid 

 at very high and very low temperatures. Its com- 

 binations when they are parts of living organisms 

 are then also the more or less metamorphosed pro- 

 ducts of such, and found in either solid, liquid, or 

 gaseous form. Thus the pre-eminent adaptation 

 of this element to serve as a means of giving some 

 degree of temporary stability to the combinations 

 formed with it by the other three above mentioned 

 is made evident. 



The whole group of secondary life elements are 

 adapted to serving a similar purpose. The mere 

 addition, however, of this group is very important, 

 for it greatly increases the possible number of 

 variations in new combinations. The vast extent 

 of the increase thus effected can only be appreciated 

 when it is considered in how many ways the prop- 

 erties and affinities of these elements of the second- 

 ary group differ from those of the primary. 



How suggestive of the infinite protean variety of 

 forms of life is this infinite mobility of three ele- 

 ments, joined to the possibility of temporary sta- 

 bility added by the fourth and by the secondary 

 group. 



The atoms, molecules, and compounds of such 

 extremely mobile substances must be exceedingly 

 sensitive to the slightest alterations in the incident 



