IOC VIEWS OF THE MICROSCOPIC WORLD. 



i 



CHAPTER V. 



CRYSTALLIZATIONS. 



" The crystal drops 

 Shoot into pillars of pellucid length, 

 In forms so various, that no powers of art, 

 The pencil or the pen, may trace the scene. 

 Here glittering turrets rise, upbearing high 

 Large growth of what may seem the sparkling trees 

 And shrubs of fairy-land And fretted wild, 

 The growing wonder takes a thousand shapes 

 Capricious." COWPER. 



ONE of the most beautiful discoveries of science is that which reveals the sin- 

 gular fact, that when bodies pass from the liquid to the solid state, with a 

 proper degree of slowness, they assume forms peculiar to themselves, which are 

 often characterized by great elegance and beauty. These configurations are 

 termed crystallizations, and each crystalline substance is regarded as having an 

 original form, called the primitive crystal ; a number of which, combining in 

 various ways, frequently give rise to a rich assemblage of the most exquisite 

 and symmetrical figures. 



The greater part of the solid bodies that compose the mineral crust of the 

 globe are discovered in a crystallized state. This is true, for instance, of granite, 

 which consists of crystals of quartz, feldspar, and mica ; and vast hilly ranges 

 of clay-slate are likewise constituted of a multitude of regular forms. The 

 body before crystallization may exist in the fluid state, either from combining 

 with a liquid, or from the action of fire. Brine is an instance of the first condi- 

 tion. Here the salt is thoroughly dissolved, so that a particle cannot possibly 

 be seen ; but if the solution is slowly evaporated, the salt again appears in the 

 form of cubes. An example of the second mode of action is afforded in the 

 case of sulphur, which, when melted and suffered to cool gradually, shoots out 

 into crystals, which, if undisturbed, are soon blended into a compact mass. 

 The original atoms are so inconceivably small, that not only do they escape the 

 unaided eye, but even when it is assisted by the most powerful glasses they still 

 elude its utmost range. Nevertheless, when, in the act of crystallization, 

 particle begins to unite with particle, the microscope is of great utility, during 

 the earlier stages of the process, and crystals of the richest configuration are 

 then seen forming immediately under the eye, branching in every direction, with 

 the most wonderful regularity and symmetry ; and often bearing a striking re- 

 semblance to the most beautiful and graceful foliage, or crowding together iii 



