OF ARTS AND SCIENCES : JANUARY 28, 1863. 103 



base, which was found in it when uncombined, by the former anal- 

 yses. 



The liquid which had been decanted from the crystals just described, 

 let fell, after standing well covered for some hours, a snow-white crys- 

 talline powder in considerable quantity. This powder, which seemed 

 to be free from crystals of hydrate of baryta, when compressed be- 

 tween paper became of a plastic or cheesy consistency. It was not 

 washed. The analysis gave the following results: 0.566 gr. weighed, 

 after remaining in vacuo over sulphuric acid till the weight became 

 constant, 0.4232 ; of this, 0.423 gave 0.2076 Ag CI, 0.3476 Ba O S 0., 

 and 0.073 Al, O3 , whence we have the composition, 



Equivalents. 

 Ba CI 26.58 1.00 



BaO 20.79 1.06 . • 



AI2O3 12.90 0.98 



HO (14.51) 6.31 



Aq _25.22 10.98 



Too 



Aq designating the water lost in vacuo. The formula of the salt is 



then 



Ba CI, Ba AI2 O3 , 6 H + 1 1 Aq. 



From the diflBculty of freeing a body of such consistency from all 

 adhering liquid, and its tendency to absorb carbonic acid during the 

 requisite manipulations, it is very probable that the water may not be 

 correctly given by the above figures. 



The aluminate of baryta in the double salt has the composition 



BaO 61.71 



• Al O3 38.29 



100 



which differs little from that previously found for the neutral aluminate. 

 We know then, in the crystalline state, the following compounds of 

 alumina and baryta : — 



A neutral aluminate described by M. Deville, 



BaO, AI2O3, 4 HO; 

 a dialuminate of the formula 



2 Ba 0, Ab Os , 6 H ; 

 a double salt of aluminate of baryta and chloride of barium, 



3 Ba CI, Ba AI2 Os , 7 H O ; 

 and a second double salt, containing the same simple salts, and com- 

 posed of g^ ^^^ Ba AI2 O3 , 6 H + 1 1 Aq. 



