102 PROCEEDINGS OF THE AMEPJCAJiT ACADEMY 



deposits on evaporation crystals, appareiitly rhombic tables and prisms, 

 which are not so hard and do not attach themselves so firmly to the 

 glass as the crystals of the dialuminate. They contain chlorine, and 

 are soluble in hot water, giving a slightly turbid solution : cold water 

 dissolves them less easily, but does not extract the chlorine, which is 

 found in the washings until they are completely dissolved. In concen- 

 trated solution of baryta they were only partially soluble ; what re- 

 mained, after being dried by pressure in paper, was free from chlorine 



and composed of 



BaO 62.11* 



AI2O3 37.89 



100 



being very nearly the composition of the aluminate previously obtained, 

 and probably as a double salt, by fusing alumina and carbonate of ba- 

 ryta with chloride of sodium, — a neutral aluminate of baryta with slight 

 excess of base. In the moist state it was little soluble in very concen- 

 trated solution of baryta, but dissolved at once on dilution with water. 



On repeating the experiment I failed to obtain this body ; owing 

 perhaps to insufficient concentration of the baryta, the crystals dis- 

 solved in it without residue. 



The crystals of the double salt, dried between folds of paper, lost in 

 vacuo over sulphuric acid 0.23 per cent, evidently adhering moisture. 

 0.7137 gr. then gave 0.6078 Ag CI, 0.6692 BaO, S03,and 0.0692 

 AI2 O3 ; from which their composition appears to have been 



100 



and is represented by the formula 



3 BaCl, BaO AI2O3, 7 H 0. 

 The aluminate contained in the double salt consisted of 



Ba 62. .50 



AI2 O3 37. .50 



100 



The aluminate thus appears to have had in combination with chloride 

 of barium almost exactly the same composition, the same excess of 



