352 HISTORY OF MINERALOGY. 



The Second System of Berzelius, though not tenable in its rigorous 

 form, approaches far nearer than any previous system to a complete 

 character, bringing together like substances in a large portion of its 

 extent. The System of Mohs also, whether or not unconsciously 

 swayed by chemical doctrines, forms orders which have a community 

 of chemical character ; thus, the minerals of the order Haloide are 

 salts of oxides, and those of the order Pyrites are sulphurets of metals. 

 Thus the two methods appear to be converging to a common centre ; 

 and though we are unable to follow either of them to this point of 

 union, we may learn from both in what direction we are to look for it. 

 If we regard the best of the pure systems hitherto devised as indications 

 of the nature of that system, perfect both as a chemical and as a natu- 

 ral-history system, to which a more complete condition of mineralogical 

 knowledge may lead us, we may obtain, even at present, a tolerably 

 good approximation to a complete classification ; and such a one, if we 

 recollect that it must be imperfect, and is to be held as provisional 

 only, may be of no small value and use to us. 



The best of the mixed systems produced by this compromise again 

 comes from Freiberg, and was published by Professor Naumann in 

 1828. Most of his orders have both a chemical character and great 

 external resemblances. Thus his Haloides, divided into Unmetallic and 

 Metallic, and these again into Hydrous and Anhydrous, give good 

 natural groups. The most difficult minerals to arrange in all systems 

 are the siliceous ones. These M. Naumanu calls Silicides, and subdi- 

 vides them into Metallic, Unmetallic, and Amphoteric or mixed ; and 

 again, into Hydrous and Anhydrous. Such a system is at least a good 

 basis for future researches ; and this is, as we have said, all that we can 

 < at present hope for. And when we recollect that the natural-history 

 principle of classification has begun, as we have already seen, to make 

 its appearance in our treatises of chemistry, we cannot doubt that some 

 progress is making towards the object which I have pointed out. But 

 we know not yet how far we are from the end. The combination of 

 chemical, crystallographical, physical and optical properties into some 

 lofty generalization, is probably a triumph reserved for future and dis- 

 tant years. 



Conclusion. The history of Mineralogy, both in its successes and by 

 its failures, teaches us this lesson ; that in the sciences of classification, 

 the establishment of the fixity of characters, and the discovery of such 

 characters as are fixed, are steps of the first importance in the progress 

 of these sciences. The recollection of this maxim may .aid us in shap- 



