as a Branch of Natural History^ S^c. 221 



The relative value to be assigned to these characters ; 3d, The 

 use which is to be made of these characters, according to their 

 greater or lesser value in the formation of classes, families, 

 genera, &c. 



§ 18. Finally, under the title of Classification, we shall give a 

 specimen of the first and most important divisions of the mineral 

 kingdom, established under the guidance of the rules previously 

 established, which are those of the natural method of classifica- 

 tion, a method which is neither arbitrary nor exclusive, which 

 does not confine itself to the use of certain particular sets of 

 properties or characters, whether chemical, physical or external, 

 but which, in each individual being as well as in the assemblage 

 of them, considers the whole of their properties, and endeavours 

 to arrange together these beings, according to their most nume- 

 rous, and chiefly to their most important analogies. 



II. MINERAL CHEMISTRY AND PHYSICS, OR AB- 

 STRACT CONSIDERATIONS ON THE CHEMICAL 

 AND PHYSICAL PROPERTIES OF MINERALS. 



Sect. I. — Minerals considered according to their chemical 



COMPOSITION AND PROPERTIES. 



A. Oftlie Elements and of their mode of combination ; of Chc" 



mical and Mechanical Mixtures. 



§ 19. List of the elements. — Various modes of combinations. 

 — Definite proportions. — Chemical and mechanical mixtures. 



B. Of the means of recognising the composition and the chemical 



properties of Minerals. 



§ 20. Qualitative analysis or essays in the dry way ; theory 

 of the blowpipe, and its application ; essays in the humid way. 

 General idea and examples of the quantitative analysis of mine- 

 rals. Calculation of the analysis. Berzelius's electro-chemical 

 theory of combination. Chemical and mineralogical formulae. 

 Synthesis ; account of BecquerePs mode of forming crystallized 

 substances by the action of weak electricity. 



