382 Reflections on seme Mineralogical Systems 



be more distinct, and the-specific gravity greatly augmented, 

 as the spaces otherwise empty or occupied with air shall be 

 filled with heavier matter. The action of chemical men- 

 strua may likewise be modified ; and if a molecule of a sub- 

 stance easily soluble is surrounded with molecules of 

 another which resists chemical solvents much longer, the 

 former may be in some measure protected from their power. 

 Other effects may take place ; but, we repeat it, the inte- 

 gral molecule remains the same. Now, in the ferriferous 

 carbonated lime we do not find the same Variety of forms 

 as in the simple carbonate ; the former is opaque, the latter 

 is transparent ; the one has lines which seem to mark a 

 direction of the cleavage more than in the other; the 

 specific gravity of the first is 3*784, that of the second is 

 2-718 ; and the ferriferous carbonate is more easily dissolved 

 in acids. These are all the phenomena which result from 

 the interposition of extraneous substances in the empty 

 spaces between the molecules of one of the bodies exhibited 

 in this example. 



EXAMINATION OF THE IDENTITY/ AND UNIFORMITY OF 

 THE INTEGRAL MOLECULE. OBJECTIONS ANSWERED. 



But I shall be told that the molecule differs, since there 

 is a direction of the cleavage more in the one than in the 

 other. It is the foreign substances which render the junc- 

 tures more sensible in one case than in another ; and it 19 

 possible that the same junctures exist in the simple as well 

 as in the ferriferous carbonate, without our having as yet 

 commonly observed them. I can almost venture to assert 

 that thev do exist. I have a specimen of carbonated lime 

 very white and very well crystallized in an obtuse rhomboid 

 of a primitive form, and of the same specific gravity as the 

 simple ordinary carbonate, but of a milky transparence, 

 and in which the lines are as distinct as in any specimen 

 whatever of ferriferous carbonated lime. This specimen, 

 nevertheless, presents in analysis no trace of any substance 

 foreign to the purest Iceland spar. It is therefore very pro- 

 bable that simple as well as ferriferous carbonate may be 

 divided in the direction of the great diagonal : hence it is 

 expected to overturn the system of M. Haiiy. But in all 

 that we know, and all that we seek to know, it is uniformly 

 our own horizon which we substitute for the limits of na- 

 ture. M. Haiiy has found in carbonated lime three direc- 

 tions of the cleavage parallel to the faces of an obtuse 

 rhomboid, and no more. He stopped there, and has not 

 wandered in the regions of imagination. Although his 



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