P. Eskola — Silicates of Strontium and Barium. 343 



The specific gravity lias been determined by Briigel- 

 mann (loc. cit.) as 4.750. 



According to H. Moissan, 16 strontium oxide melts more 

 easily than calcinm oxide, but nothing more is known 

 abont its melting temperature. 



Wyckoff 17 has determined, by Debye and Scherrer's 

 method, the crystal structures of CaO, SrO, BaO and 

 mixtures of CaO with SrO and BaO, respectively, in 

 samples prepared by me. His results have interest for 

 us in so far as they prove SrO to be perfectly isomor- 

 phous with and to form a series of solid solutions with 

 CaO. 



The System BaO-Si0 2 . 



The quenching experiments pertaining to the system 

 BaO.SiOo are described in table II. 



Table II. 



Composition v 



rt. per 



cent 









Compounds 





Oxid 



es ! 



BaO. 



2BaO. 



Temper- Time 



BaO 



Si0 2 2Si0 2 



3Si0 2 



ature °C minutes Resulting phases 









Liquidus of tridymite 



40 



60 







1551 90 Glass and tridymite 



45 



55 







1472 120 Glass 



45 



55 







1447 90 Glass and tridymite 









Euteetie tridyniite-Ba0.2Si0 2 



45 



55 







1372 135 " Tridymite and Ba0.2SiO, 



47.5 



52.5 







1390 120 Glass 



47.5 



52.5 







1377 60 Glass and tridymite 



47.5 



52.5 







1373 120 Ba0.2SiO, and tridymite 



50 



50 







1398 120 Glass 



50 



50 







1385 60 Crystals and glass 



50 



50 







1369 120 Tridymite and Ba0.2SiO- 









Melting point of Ba0.2Si0 2 



55.98 



44.02a 







1425 90 Glass 



55.98 



44.02 







1421 30 Glass 



55.98 



44.02 







1419 60 Ba0.2Si0 2 (with some gli 





Liquidus 



of the solid solutions Ba0.2Si0 2 -2Ba0.3Si0 2 



58 



42 



71 



29 



1441 60 Glass 



58 



42 



71 



29 



1435 60 Glass 



58 



42 



71 



29 



1432 60 Glass and mix crystals 



60 



40 



42 



58 



1448 60 Glass 



60 



40 



42 



58 



1443 60 Glass and mix crystals 



61.25 



38.75 



23.9 



76.1 



1451 60 Glass 



61.25 



38.75 



23.9 



76.1 



1448 60 Glass and mix crystals 



IC H. Moissan, Ann. Chem. Phys., (7) 4, 136, 1895. 

 17 Ealph W. G. Wyckoff, unpublished data. 



