ton 



280 FIXED ALKALIES AND ALKALINE EARTHS. 



sia, it is evident that anhydrous sulphate of mag- 

 nesia is a compound of 



Sulphuric acid 

 Magnesia 



7-5 



The salt being neutral, and 5 being the atomic 

 weight of sulphuric acid, it is plain that 2%5 must 

 represent the atomic weight of magnesia. 

 posi- 2. By a careful analysis of the crystallized 



of sul- J \ 



sulphate or magnesia, I have ascertained that it 



magnesa. . i 



is a compound ot 



1 atom sulphuric acid = 5 

 1 atom magnesia = 2 5 



7 atoms water = 7 '87 5 



15-375 



So that an integrant particle of it weighs 15-375. 

 When 15*375 grains of these crystals are heated 

 properly, the whole water may be driven off 

 without the loss of any sulphuric acid or magne- 

 sia 5 for the weight of the anhydrous salt is 

 exactly 7*5 grains. 15-375 grains of crystallized 

 sulphate of magnesia just precipitate all the ba- 

 rytes contained in a solution of 13*25 grains of 

 chloride of barium. 

 Muriate of 3. Muriate of magnesia is a deliquescent salt ; 



magnesia. . i i i 



but it may be obtained in large transparent crys- 



