620 



BRIDGMAN. 



or Cp placed near a transition line, on one side, shows that the phase 

 on that side of the line has the greater compressibility, thermal expan- 

 sion, or specific heat. In addition, the Arabic numerals placed in the 

 regions of the several phases show the crystalline systems. The 

 Roman numerals give the designation of the phases used in the 

 early part of this paper. The information about the crystalline 



4 G 8 10 2 4 i; S 10 2 4 6 

 Pressure in Thousands of Kilograms per Sciuare Centimeter 



Figure 16. Collection in one diagram of the several phase diagrams. The 

 Arabic numerals refer to the crystalline systems as foUows: 



1, Quasi-trigonal. 



2, Orthorhombic, quasi-tetragonal, optically negative. 



3, Orthorhombic, quasi-tetragonal, optically negative. 



4, Monoclinic, quasi-tetragonal, optically positive. 



5, Tetragonal, optically positive. 



6, Rhombohedric, quasi-cubic, optically positive. 



7, Cubic. 



8, Rhombohedric, type of calcite, optically negative. 



systems has been taken directly from Wallerant's Cristallographie, a 

 work which deserves to be better known in this country. 



It is evident in the first place that AgNOs belongs in a class apart 

 from the other five univalent nitrates. Its phase diagram is entirely 

 different in character, and it is known not to crystallize isomorphously 



I 



