26 



Allen, etc.- 



■Diopside and- its Relations 



isomorphous substances. In either case the volumes would 

 form a straight line between the two constituents. DC is 

 made up of diopside mix-crystals with magnesium silicate. 

 The limit of the solubility of the latter in diopside is at about 

 70 to 72 per cent MgSi0 3 as determined by the specific volume 



Table IV. 



Specific Gravities and Specific Volumes of Mixtures of 

 CaSi0 3 and MgSi0 3 . 



Ofo J 



tfftS 



8 



u 



10 



a 



20 



it 



30 



a 



40 



a 



45 



it 



46-3 



tt 



47*5 



a 



50 



a 



55 



a 



60 



a 



65 



it 



70 



a 



72 



a 



75 



a 



80 



a 



85 



a 



90 



a 



95 



a 



100 



a 



3p. gr. 



Sp. v. 



2-912 



•3434 



2-965 



•3373 



2-947 



•3362 



3-046 



•3283 



3-111 



•3215 



3 201 



•3125 



3-229 



3096 



3-237 



•3089 



3-236 



•3090 



3-241 



•3<»86 



3-246 



•3081 



3-245 



•3<!82 



3-255 



•3()72 



3-241 



•3086 



3-241 





3-229 



•3096 



3-211 



•3115 



3-212 





3-205 



•3120 



3-198 



•3127 



3-196 



•3129 



3-196 



•3127 



3-194 



•3130 



3*198 



•3127 



3-192 



•3132 



3-188 



•3137 



3-181 



•3140 



3-193 



•3132 



Where two different numbers are given, they belong to different prepara- 

 tions. 



curve. The microscope sets the limit at about 66'5 per cent. 

 The discrepancy is probably due to experimental error in the 

 specific gravity determinations caused by the presence of bub- 

 bles in the grains. An inspection of the curve shows that the 

 volumes of these solid solutions all lie above a line joining B 

 and D. They are, therefore, greater than the volumes calcu- 



