Mixter — Heat of Combination of Acidic Oxides. 129 



and alumina than used in the tests mentioned, it is evident 

 that any error due to solubility of alumina is insignificant. 

 Moreover, varying portions of sodium peroxide do not affect 

 thermal results. 



Experiments. 



1 2 



Aluminium oxide (amorphous) 3'357 grams 4*313 grams 



" " in residue.. — -026 " —'160 " 



" " reacting... 3-331 " 4-153 " 



Carbon 1*218 " 1-294 " 



Sodium peroxide 21* u 25- " 



Water equivalent of system.. 3528* " 3559* " 



Temperature interval 4*245° 4*479° 



Heat observed 14977° 15941° 



" of oxidation of carbon . . —13520° —14363° 



" " " " iron -60° —60° 



For 1 gram of amorphous alumina 

 combining with sodium oxide 



Aluminium oxide (crystalline) 

 " " in residue. _ 

 " " reacting 



Carbon , 



Sodium peroxide. 



Water equivalent of system. - 

 Temperature interval «. 



Heat observed 



" of oxidation of carbon.. 

 " « " " iron 



For 1 gram of crystalline alumina 



1397° 





1518° 



419° 





365° 



3 





4 



4*517 grams 

 — 1*174 

 3*343 " 

 0-809 " 

 17- 

 3087* 

 3-225° 



4*038 grams 



— *854 " 



3*184 " 



0*814 " 



17* " 



3036- " 



3*355° 



9956° 



— 3979° 



— 32° 





10185° 

 9035° 



— 64° 



945° 

 283° 



1086 ( 

 310 c 



In experiment 3 the pressure in the bomb was 16 cm higher 

 after the combustion than before, and the calculated correc- 

 tion for the oxygen set free was 30°. This is not included in 

 the result above, as changes in pressure were not observed in 

 experiments 1, 2 and <4 with alumina. In experiments 3 and 

 4 about two-thirds as much carbon was used as in 1 and 2. In 

 order to find if the ratio of the carbon to the alumina influ- 

 ences the result, a calorimetric test was made in which the 

 amounts of carbon and amorphous alumina were nearly the 

 same as in experiments 3 and i. The result was the same as 

 in 1 and 2, as shown in the following experiment : 



