270 Dr T. THOMSON'S Account of the 



and the chemical constitution the same. The only difference 

 that can be laid hold of is the shade of colour, which constitutes 

 too insignificant a distinction to be adopted as a specific diffe- 

 rence. Whoever will compare the constituents of cinnamon- 

 stone, as determined by KLAPROTH, ARFVEDSON, NORDENSKIOLD, 

 C. G. GMELIN, with the analyses of the different varieties of gar- 

 net by TROLLE'-WACHMEISTER, will be satisfied that the chemical 

 constitution of both is the same. 



Captain LEHUNT analysed at my request a very fine specimen 

 from North America sent me by Dr TORREY of New York, which 

 had the colour of cinnamon-stone, and the crystalline figure and 

 hardness of garnet. Its specific gravity was 3-631. Its consti- 

 tuent parts were as follows : 



Silica, ...... 39.826 



Lime, 30.574 



Alumina, 29.141 



Protoxide of Iron, . . 9.459 



100 



My opinion respecting the garnet, founded on a pretty co- 

 pious induction of facts, is, that there exist in nature three dis- 

 tinct species, composed as follows : 



1 atom silicate of alumina, 

 1 atom silicate of iron. 

 1 atom silicate of alumina, 

 1 atom silicate of lime. 

 1 atom silicate of lime, 

 1 atom silicate of iron. 



The greater number of garnets consists of mixtures or combi- 

 nations of these three species in various ways. Now, the cinna- 



