252 



Chloride of Aluminium and its Analysis. 



These results give the following values for the composition of 

 alumina. 



"Oxygen, 

 Aluminium, 



x' x" z z' 



2.10843 2.10906 1.49496 1.5000004 

 1.85379 1.85430 1.31425 1.3188017 



Al 



umina, 



3.96222 3.96336 2.80921 2.8188021 



o< 



V y y 



Oxygen, 1.94683 2.07404 2.08395 



Aluminium, 1.71166 1.82350 1.82274 



^Alumina, 3.65849 3.89754 3.90669 



The values of x', x" ^ y, y', y" , make a distant approximation to 

 the ratio of a deutoxide. More confidence is placed in the values 

 of z and z' , than in the others, for reasons already explained, z is 

 calculated from the results of my OAvn experiments, and the atomic 

 number for aluminium, deduced from the inverted numbers of alu- 

 mina, as given by Berzelius, (Vide tables i, i' and k.) The value 

 of z' is calculated from the results of the preceding analysis and 

 the atomic number deduced from those results independently. (Vide 

 tables a, j, j', and k.) 



The values of z and z' in tables k and 1, calculated upon the sup- 

 position that the chloride analyzed was a neutral chloride, approach, 

 very near to the ratio of a protoxide while in tables n and o calculated 

 upon the supposition that the chloride was a sesquichloride, the val- 

 ues indicate a sesquioxide. It follows then that if alumina be con- 

 sidered a protoxide, the chloride analyzed, was a protochloride, if 

 a sesquioxide, the chloride is a sesquichloride. 



The atomic weight of aluminium, is then, according to these 

 experiments 0.87920118, or 1.31880177 according as we consider 

 alumina a proto, or sesquioxide. 



From the circumstance that alumina is isomorphous with the oxide 

 of chromium and the peroxides of iron and manganese it may be 

 supposed a sesquioxide, and its composition would be 



Oxygen,. 1.5000004-^1 J atoms = 53.2141 



. Aluminium, 1.3188017 = 1 atom =46.7859 



Alumina, 



2.8188021 



100.0000 



