300 Reflections on 'some Mlneralogical Systems. 



specie^ together, to form masses of a perceptible magni- 

 tude. If the result appears to be invariable, at least in 

 what relates to the general mode of aggregation, should it 

 be every where the same, we shall be obliged to admit that 

 nature here also works by immutable laws, and that we 

 must find means to comprehend them in the system of 

 science. These masses will therefore be mixed species, 

 and appertain to geognosis; they will be strictly gcognostic 

 species, seeing that the simple minerals of which they are 

 composed are so, that in their union they have observed 

 invariable laws, and that it is no more difficult to pro- 

 nounce on three species united, provided that the specific 

 character be there distinctly visible, than on three species 

 when thev are separated. 



The minerals in the fourth condition constitute the 

 greatest difficulty in mineralogy. This science here finds its 

 cryptogamia. 



The analogy which led us to assign a place to the con- 

 fused mixtures of molecules of one species, abandons us as 

 soon as we wish to apply it to pieces which are composed 

 of imperceptible molecules of divers species. In the sup- 

 position that we cannot discern those molecules of each 

 species, it is impossible to refer the piece with propriety to 

 any one. ,But if we observe in these masses the same con- 

 stancy of character as in the mixtures of perceptible species, 

 although we can demonstrate nothing in their constitution, 

 we must assign them a place, and the appreciation of na- 

 ture here be abandoned in some measure to the conscience 

 of the observer. The tirst difficulty is to know what is the 

 number of different species, the molecules of which have 

 contributed to the formation of the mass. Suppose an ag- 

 gregate in v\ hi eh we cannot discover any form of mole- 

 cule, which at the same time effervesces with acids, and 

 emits fire with steel, of which one part dissolves in muriatic 

 acid, leaving carbonic acid gas to escape, while the other is 

 entirely insoluble ; that the dissolved part be lime, the 

 other silica *, To what species shall it be referred ? Is it 

 even possible to refer it to any ? There is carbonated lime 

 and silica, and our operations inform us that there has been 

 a mixture of the two species. But this advantage, how- 

 ever weak it may be, no longer exists, if all the molecules 

 which are found in the same mass act in the same manner 

 with the same chemical and physical instruments; and wc 

 have no more resources to learn if it is composed of mole- 

 cules of one species, of two, or of several. I shall cite the 

 agate, jaspjr, hornstUnc, and the long list of species which 



are. 



