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though they are toto ccelo different in their habit, that 

 they are one and the same galena? I think it could be 

 only on great mineralogical faith, such as no one can in- 

 spire him with, as he studies alone ; it is more probable 

 that he will think himself mistaken, and such mistakes 

 often repeated, occasioned by the analytical method, 

 will disgust the most herculean courage. Would not 

 the same end be better obtained, and triplicate trouble 

 spared the student, by adding only to the third class, 

 or rather catalogue, that it is also found in cubes, and 

 has triple perpendicular cleavage ? But granting the 

 partition into three classes, as it is, fluor is found most 

 frequently in cubes, and yet the student shall not be 

 able to find it in the first order of the first class, where 

 it should be 5 it is to be found in the third order, the 

 Octahedron, perhaps because Mohs has called it Octa- 

 hedral fluor haloide, on account of the cleavage ; but 

 Mohs has not written for students, left to their own re- 

 sources ; and moreover, he assigns, in his Mineralogy, 

 the fluor as an example of cubes. Indeed, I know 

 only of two localities where it is found in Octahedrons ; 

 and so the author should have put at least the fluor at 

 the end of the first order, with reference to the third. 

 On the contrary, the leucite and analcime are included 

 in the first order of the first class. The author himself 

 observes, that the trapezohedron is the only existing 

 form of the first. Why did he not add, that it is also 

 the most common of the second? It is true that the 

 order trapezohedron is wanting in his method, but I 

 think it should have been added, to include in it, the 



