ORDER II. PURE ATMOSPHERICXWATKIi. 21 



ORDER 1 1. WATER. 



GENUS I. ATMOSPHERIC- WATER. 



1. PURE ATMOSPHERIC-WATER. 



Pure Atmospheric "Water. JAM. Man. p. 3. Weich- 

 Wasser. Hart-Wasser. HAUSM. III. S. 766. 773. 



Amorphous. Transparent. Liquid. 

 Sp. Gr. := I'O. Without odour or taste. 



OBSERVATIONS. 



1. Pure Atmospheric-water consists of 



Oxygen 88-94. 



Hydrogen 11 '06. BERZELIUS. 



In its natural state, it generally contains several earthy 

 substances, salts, or acids, in a state of solution, which 

 sometimes exercise a considerable influence upon its taste, 

 odour, and specific gravity. Thus are formed the different 

 kinds of hard water, of acidulous and bitter waters, and 

 sea-water, which by some naturalists have been considered 

 as particular species. If the temperature be sufficiently 

 high or low, its form of aggregation is changed ; and in- 

 stead of water, there appears steam or ice. The crystals 

 of ice or snow, of which a great number are described 

 and figured by Captain Scoresby, are commonly said to be- 

 long to the rhombohedral system. But the figures of the 

 crystals of snow, being commonly like that of a star with six 

 radii, very nearly resemble the regular compositions of di- 

 prismatic Lead-baryte, Kg. 38., and of other minerals 

 belonging to the prismatic system. Dr BREWSTER has 

 found, on the other hand, that ice exhibits in polarised 

 light most distinctly the single system of coloured rings, 

 depending t upon the existence of a single axis of double 

 refraction. It will therefore be prudent to leave the 

 question still undecided, to which system of crystalli- 

 sation these forms belong, which will depend upon fu- 



