269 



100,0 



Although a small excess of Li^O was still present, the substance 

 could be considered as practicail}' pure LiAlO^, — the more so, 

 as on heating, a certain amount of Z/2t>^ always volatilizes gradually. 

 A preparation, heated only shortly at 1600° C. contained, as ana- 

 lysis showed us, only 19,34 7„ Li^O and 80,65 7„ .4/, O3 ; no further 

 change had occurred than that the crystals of the original prepa- 

 ration had got much lar</er dimensions, loJdle preserving their gene- 

 ral properties. At 1625' (J. the substance shows no trace of melting, 

 but decomposes partially, by the volatibility of the Li^O. The pla- 

 tinum is strongly attacked, Li^O^^ being formed, and thus the alumi- 

 nate cannot be heated at higher temperatures, without changing its 

 composition. The meltingpoint can thus be hardly determined; the 

 substance must have iieen changed a long time before already into 

 Al^Oi, with perhaps a slight admixture of some lithiumoxide. Even 

 in a "hollow thermoelement", we were not able to melt the substance, 

 notwithstanding it being heated up to 1625° C. 



Microscopically the aluminate shows large, round-edged, hexagonal 

 or octogonal plates (tig. 12), ^vitll a i-elatively high birefringence 



Fig. U. 

 Crystals' of LUhiumaluminale. (X Nicols). 



