Calcium Metasilicate. 



101 



Table III.* 

 Melting; of Pseudo-Wollastonite. Curve 2. 





Rise in 



Melt. 



Rise in 



Risein 



Control. 



Rise in 



Melt. 



Rise in 

 2 min. 



Risein 





2 min. 





2 min. 



^ rnin. 





2 min. 





i mm. 



15616 



• 







16109 



33 

 15993 



8 



8 



72 



15604 







66 



16001 

 008 



7 



7 



688 





70 





175 



27 

 021 



6 



7 



72 



674 







70 



028 

 034 



6 

 6 



760 





66 





245 



26 

 047 



7 

 7 



76 



740 







70 



054 



060 



6 



7 



836 





66 





315 



28 

 074 



7 

 8 



77 



806 







65 



082 

 092 



10 

 12 



913 





62 





380 



69 

 126 



16 

 25 



74 



868 







90 



151 



183 



32 



987 





55 





470 



247 





59 



923 



45 





108 



578 



398 





16046 63 



968 

 977 





9 



8 









the silicates. Molten calcium vanadate brings about the rever- 

 sion at temperatures below the inversion point by the forma- 

 tion of a solution from which the more stable wollastonite 

 crystallizes in well-formed prismatic crystals. Excess of lime 

 or silica also facilitates the reversion. 



Following the invariable rule, the change W„ — >Wj, occurs 

 with an absorption of heat. The volume change which 

 accompanies this transformation is so slight that it is uncertain 

 which form is the more dense. 



The pseudo-wollastonite melts at 1512° to a comparatively 

 thin liquid, which almost always crystallizes above 1200° on 

 cooling down again. This explains why true wollastonite can- 

 not generally be formed from a liquid of its own com- 



* AH the numbers in this table are 7 microvolts too high, on account of a 

 slight, unavoidable leakage current through the insulation of the hot fur- 

 nace. Hence the true melting point is 16053 microvolts, as given in the 

 previous table. 



