1815.] Berzellus's System of Mineralooy. 303 



present day, has led him to apply the doctrine of chemical propor- 

 tions to all the different departments of the science. The object of 

 the present little work is to show that minerals are all real ciiemical 

 compounds, that every species consists of constitue-nts combined 

 according to the laws of chemical proportions, and that they are 

 susceptible of an accurate chemical airangenieiit into classes, 

 orders, genera, and species, according to the nature of the sub- 

 stances of which they are composed. 



I'he work bears evident marks of the great abilities and extensive 

 knowledge of the author, and must suggest many im^'oitant and 

 useful ideas to every mineralogist who will read it uith sufficient 

 attention; though perhaps a more deliberate consideration of the 

 subject, and a more mixuite acquaintance with the details of mine- 

 ralogy, might have led to a modification of some of the opinions 

 which Professor Berzelius has advanced ; for instance, he seems to 

 rate the knowledge of the external characters of minerals very low, 

 and to consider the whole of the science of mineralogy as confined 

 to an acquaintance with the constituents of which every mineral is 

 composed. But it is necessary to recollect that, before the chemical 

 analysis of any mineral can be of impoitance to the science, or 

 lead to any useful inferences, we must be sure that the specinrien 

 which we subject to analysis belongs really to the species which we 

 suppose, and that it is quite pure and unmixed with any osher 

 mineral. Now this knowledge can only be acquired by an ac- 

 quaintance with the external characters of minerals — a !)i'anch of 

 knowledge which must therefore precede all useful chemical ana- 

 lysis. Hence it must always serve as the basis of our mineralogical 

 knowledge. In fact, the labours of the chemist, who applies his 

 practical skill to minerals, can only be of utility when he takes 

 care to make his experiments upon correct and pure specimens. 

 If a chemist, for example, analyze a specimen of mica, and pub- 

 lish the result under the name of qji analysis of tide; or if he give 

 the name of slilbite to what in reality is ineso-ype, his labours, in- 

 stead of being useful, mu?t be injurious to mineralogy. Yet these 

 mistakes have been committed by chemists of acknowledged skill. 

 The same injurious effects arise from the analysis of impure speci- 

 mens, as when a mixture oi felspar and fjiia->-tz, or of Jelspar and 

 garnet, is analyzed under the name otj'clspar. Unless 1 am much 

 mistaken, errors of this kind have been lately committed by some 

 of the most accurate analysts of the present day. 



The knowledge of the constituents of minerals is always interest- 

 ing, and in many cases indispensable. Thus the art of mining is 

 founded on the knowledge of the different metals which may be 

 extracted from the different ores. But to conceive that the whole 

 science of mineralogy consists in a knowledge of the constituents of 

 minerals, and that every thing else is of no consequence, is what no 

 person can |>ossibly do who has taken the requisite pains to make 

 himself actjuainted with the science. The diainontl wiis as accu- 

 rately distinguished by its external properties, and was Hpplicd to as 



