REFORM OF MIXERALOGICAL SYSTEMS. 351 



definite chemical constitution. Our ignorance may surprise us; but it 

 may diminish our surprise to recollect, that the knowledge which we 

 seek is that of the laws of the physical constitution of all bodies 

 whatever ; for to us, as mineralogists, all chemical compounds are 

 minerals. 



The defect of the principle of the natural-history classifiers may be 

 thus stated : in studying the external characters of bodies, they take 

 for granted that they can, without any other light, discover the relative 

 value and importance of those characters. The grouping of Species 

 into a Genus, of Genera into an Order, according to the method of this 

 school, proceeds by no definite rules, but by a latent talent of apprecia- 

 tion, a sort of classifying instinct. But this course cannot reasonably 

 be expected to lead to scientific truth ; for it can hardly be hoped, by 

 any one who looks at the general course of science, that we shall 

 discover the relation between external characters and chemical com- 

 position, otherwise than by tracing their association in cases where 

 both are known. It is urged that in other classificatory sciences, in 

 botany, for example, we obtain a natural classification from external 

 characters without having recourse to any other source of knowledge. 

 But this is not true in the sense here meant. In framing a natural 

 system of botany, we have constantly before our eyes the principles of 

 physiology ; and we estimate the value of the characters of a plant by 

 their bearing on its functions, by their place in its organization. In 

 an unorgauic body, the chemical constitution is the law of its being ; 

 and we shall never succeed in framing a science of such bodies but by 

 studiously directing our efforts to the interpretation of that law. 



On these grounds, then, I conceive, that the bold attempts of Mohs 

 and of Berzelius to give new forms to mineralogy, cannot be deemed 

 successful in the manner in which their authors aspired to succeed. 

 Neither of them can be marked as a permanent reformation of the 

 science. I shall not inquire how far they have been accepted by men 

 of science, for I conceive that their greatest effect has been to point 

 out improvements which might be made in mineralogy without going 

 the whole length either of the pure chemical, or of the pure natural- 

 history system. 



Sect. 4. Return to Mixed Systems with Improvements. 



IN spite of the efforts of the purists, mineralogists returned to mixed 

 systems of classification ; but these systems are much better than they 

 v,ere before such efforts were made. 



