47 



>mr|>hism, and of enantiomorphous arrangements in space, is 

 u of the most important facts in the whole domain of physical 

 ul . lu mical research, as we .shall afterwards show in detail. In 

 \. 50 the possible crystal-forms of some substances are reproduced 



an illustration of two enantiomorphous polyhedra. 

 12. With the aid of the devices employed in this chapter, 



have succeeded in finding out all possible types of symmetrical 

 nips ot the first order; i. e. of all figures which can be made to 

 >incide with themselves by rotations alone. 

 We can now use these groups, as we shall see, as a basis for the 



luction of all those other groups which possess symmetry-pro- 

 jrties of the second order too. This will be shown more exactly 

 the following chapter. 



