224 Professor Necker on Mineralogy considered 



is decomposed, or in the act itself of its decomposition, are pro- 

 per characters. But if, after its complete decomposition, and 

 when its component parts have formed new combinations with 

 other substances, ulterior operations were required, these not 

 being immediate, and the body to be characterized, having com- 

 pletely vanished from the inspection of the observer, the charac- 

 ters derived from such operations would not be proper charac- 

 ters in natural history. Hence the reason why characters of the 

 solutions of mineral bodies recognised by precipitates ought not 

 to be employed. But the direct effects of water, of the acids or 

 alkalis, of heat in whatever way it is employed, of fluxes, and of 

 the greatest number of contiivances described by Berzelius to 

 be employed with the blowpipe, having the advantage of being 

 immediately applied to the individual itself, or to a portion of, 

 or representing, the whole, are to be considered as excellent cha- 

 racters. In fact, the immediate exposition of the mineral to 

 such chemical tests is nothing else but a change in the circum- 

 stances or in the medium in which the body is naturally placed ; 

 quite analogous to the changes experimentally produced in order 

 to ascertain the specific gravity, the hardness, and the malleabi- 

 lity of a mineral. 



On the contrary, most of the experiments required for a 

 qualitative analysis by the humid way being complex, and not 

 immediate, operations, are not to be admitted among the cha- 

 racters. 



The quantitative analysis, which is the most complicated and 

 difficult, can still less be admitted among the characters, as its 

 results derive their chief value from the name and the fame of 

 the chemist who has made it. Surely the mineralogist ought to 

 be thoroughly acquainted with the results of all the analyses 

 made of the different minerals, called upon as he is to compare 

 them, in their chemical composition as well as in all their phy- 

 sical properties, for this knowledge will enable him to find pro- 

 per characters to assemble minerals allied to each other by ana- 

 logies of composition. But the analysis, or the formula denot- 

 ing its result, will never be held as a proper distinctive charac- 

 ter in the eye of a naturalist. 



§ 27. Thirdly, in examining in succession the various minera- 

 logical characters, it has often been objected to each of them, as 



