46 PHYSIOGRAPHY. 



Automolite. 



leads to the conclusion that the system of crystallization in ice is a quad- 

 rangular prism, and not a rhomboid, as was formerly supposed. It is 

 well known that no species in mineralogy, whose primitive form is the 

 rhomboid, presents crystallizations similar to the star-like figures of snow. 

 The hail-stones which fall in the spring have the form of spheric sec- 

 tions, consisting of opake, thin prisms, radiating from the centre : those 

 formed during heavy thunder storms in summer, generally, affect the 

 shape of irregular, flattish globules, consisting of columnar particles of 

 composition, but often perfectly transparent, and sometimes enclosing 

 air bubbles. 



2. Analysis. 

 By BERZEI.IUS. 



Oxygen 88-94 



Hydrogen . . . . . 11-06 



When pure, it is destitute of taste or odor. But water which flows 

 within or upon the surface of the earth, contains various earthy, saline, 

 metallic, vegetable, or animal particles, which often materially affect its 

 taste and smell, and sometimes considerabty augment its specific gravity. 

 Thus from the accidental presence of salts and acids are formed the dif- 

 ferent kinds of hard water, of acidulous and bitter waters, and sea water. 

 3. Pure atmospheric water descends from the atmosphere in the form 

 of rain, mist, dew, snow or hail ; it is also emitted from springs, and ac- 

 cumulated all over the globe in lakes, seas, &c. : in these last instances, 

 however, it is contaminated with variable proportions of saline sub- 

 stances. 



AUTOMOLITE. Octahedral Corundum. MOHS. 

 Primary form. Regular octahedron. 

 Secondary form. 



Fig. 49. 



Cleavage parallel with the primary faces. 



