ALUMINA. 313 



this sulphate of alumina, and found it composed 

 of 



Sulphuric acid 40 

 Alumina . 40*83* 



This he considers as inconsistent with 2*25 being 

 the atomic weight of alumina. But if 3'375 be 

 the atomic weight of that earth, he conceives 

 that his salt was a compound of 



2 atoms sulphuric acid 10 or 40 



3 atoms alumina . 10-125 - 40-5 



20-125 



But this is not the only view of the subject 

 which may be taken. 



I may observe, in the first place, that alumina Explained, 

 is a much weaker base than any of the other 

 earths or alkaline bodies treated of in the pre- 

 ceding chapter. Now, it is a remarkable cir- 

 cumstance, which has been particularly illustrated 

 by Berzelius, that weak bases have the property 

 of combining in a much greater number of pro- 

 portions with acids than strong bases. I have 

 ascertained by experiment that alumina and 

 sulphuric acid may be united in three propor- 

 tions j namely, 



1 atom acid + 1 atom alumina 

 1 atom acid + 2 atoms alumina 

 1 atom acid -f. 3 atoms alumina 



* Annals of Philosophy (second series) IV. 280. 



