Reflections on some Miner alogkal Systems. 379 



minerals should be of the same species ; and hitherto mu- 

 riated soda and sulphated lead are in this state. Identity of 

 chemical composition, — here are two conditions, if I have 

 rightly calculated ; and muriated soda and sulphated lead 

 are not of the same species. 



M. Haiiy himself has answered the second objection in 

 a manner which leaves nothing to be added. It is true, that 

 with the same form of integral molecule we have a different 

 chemical composition j but let us observe under what cir- 

 cumstances. 



There are three geometrical figures which perform the 

 office of integral molecule : Admirable simplicity of nature, 

 that with such slender means can compose forms in an in- 

 finite number I These figures consist of those with four 

 sides, the least number possible to contain a solid ; those 

 with five, and those with six ; all are the most simple. But 

 they are all susceptible of an infinite variety in the dimen- 

 sions of their sides and in the inclination of the faces which 

 terminate them, although all have a fixed term of regu- 

 larity towards which they tend. It is but in these terms, 

 which in this respect are the limits, that we find the iden- 

 tity of the physical with a diversity in the chemical mole- 

 cule. The repetition of regular forms which are the li- 

 mits of others, such as the cube and regular tetraedron in 

 the different species, appears to me to prove nothing against 

 the system of M. Haiiy ; on the contrary, it gives us cause 

 to admire the mechanism of nature, which delights in mul- 

 tiplying its severe and rigorous features amidst the variety 

 in which it indulges. The most regular forms are also the 

 most simple ; and I take it for an axiom, that it is but in 

 approaching simplicity that we approach nature. 



Let us examine if the reverse of this be equally true ; that 

 is to say, if with the same chemical composition we find a 

 difference in the physical molecule. There is only one case 

 well ascertained ; it is that of carbonated lime and arraoo- 

 nite. Chemists the most celebrated in the art of analysis, 

 Messrs. Vauquelin, Thenard, and Klaproth, have found no 

 difference between these two minerals ; and I acknowledge 

 that I have repeated the analysis of six different specimens 

 of arragonite, comparatively with the carbonated lime, and 

 I am convinced of their identity of composition. M. I Jaiiy 

 found a difference in the form of their integral molecules. 

 How admirable is this science, to which, — in the first years 

 of its existence, and before that time has impressed it with 

 those marks of rigour which continued observations inva- 

 riably effect, — only one objection can be made against it 



that 



