72 Scientific Notice's — Mineralogy. 



The numerical results of his analyses were as follows : 



[Jan. 



The garnet which, in its composition, constituted an excep- 

 tion to all the other varieties, is the one whose leading charac- 

 ters are given in No. 13. It contains so large a proportion of 

 silica, tliat one-half of the bases must be supposed to exist in the 

 state of bisilicates. Wachtmeisier, however, is of opinion, that 

 this variety may for the present be left out of view, because it is 

 even to the naked eye distinctly intermixed with a foreign mine- 

 ral, and it is not to be supposed tb.at the composition of a sub- 

 stance evidently impure, can be admitted to invalidate a general 

 law, which all the twelve otlier vaiieties coincide in indicating. 

 The o-arnet, indeed, possesses a peculiar tendency to crystallize 

 indiscriminately with other mineral compounds, from which it 

 differs essentially in chemical constitution ; and the presence of 

 such foreign bodies, so far from being an obstacle, appears even 

 to favour its crystallization. These foreign admixtures may be 

 often recognized in the form of dull spots on the surface of the 

 most regularly formed crystals. 



4. Colleciion of Minerals. 



In proof that mineralogy is not on the decline on this side of 

 the water, we may allude to the purchase of Hauy's collection 

 not long ago by his Grace the Duke of Buckingham; and we 



• Including some carbonic acid. 



