Mixter — Heat of Combination of Acidic Oxides. 137 



Summary. 



3Na 2 + B 2 3 = 2Na 3 B0 3 + 104200 c 



Na 2 + Al a 9 (amorphous) = 2NaA10 2 + _._ 40000 c 



Na 2 + Al 2 3 (crystalline) = 2NaA10 a + ... 30000 c 



Al 2 3 (amorphous) = Al 2 O s (crystalline) + _. 10000° 



Na 2 + Cr0 3 = Na 2 Or0 4 + -- 77000° 



Or + 30 = O0 3 + 140000° 



2Cr + 30 = Cr 2 3 (amorphous) -f 243800° 



2Cr 4- 30 = . Cr a O s (crystalline) + .1 267800° 



Cr 2 3 (crystalline) + 30 = 2Cr0 3 + 12200° 



Cr a O,(amorphous) + 30 = 2Cr0 3 + 36200° 



Na„0 -f W0 3 = Na a W0 4 + 94700° 



The results given have been obtained with substances at 

 hand and it is the intention to complete the work as far as 

 possible on the fourth, fifth, and sixth groups. 



