28 THOMAS STEERY HUNT ON A NATURAL SYSTEM IN 



the presence or absence of certain acids, alkaloids and groups of essential oils, are not 

 without significance in determining the natural affinities of plants, and, moreover, that as 

 we descend the scale of being, from the highly organized forms of the animal and vege- 

 table world to the simple crystal or the amorphous colloid mass, the external characters 

 which serre to show likeness and difference become fewer, and are often obscure and ill- 

 defined. Again, a natural system is not one subordinate to the end of identifying species, 

 but should consider objects in all their alliances and relations. Such a system, as long 

 since defined by John Ray, is one which neither brings together dissimilar species nor 

 separates those which are nearly allied, and the most important resemblances and différ- 

 ences in the mineral kingdom are in many cases those which can only be determined by 

 chemical investigation. 



§ 9. If, however, we regard as mistaken those who in their search after a natural system 

 in mineralogy have rejected the aid of chemistry, it must be said, on the other hand, that the 

 chemical mineralogists who, disregarding the relations of density and hardness or relegat- 

 ing them to a secondary rank, build systems on the results of chemical analysis, are false to 

 chemical science itself There exist, in fact, inherent and necessary relations between the 

 physical characters and the chemical constitution of inorganic bodies which serve to unite 

 and reconcile the natural-historical and the chemical methods in mineralogy. A physico- 

 chemical study of the mineral kingdom, having in view these relations, will enable us, 

 while remaining faithful to the great traditions of Werner and of Mohs, to frame a classi- 

 fication which it is believed will merit the title of a Natural System in Mineralogy. 



II. — An Attempt at a Natural System. 



§ 10. That such a system is possible was maintained by the present writer in a series 

 of papers published in 1853, 1854 and 1855, to be noticed in detail further on. In putting 

 forth, in the first named year, my conclusions as to the extension of chemical homology, 

 and the similarity of volume in isomorphous species, it was said that " these views will 

 be found to enlarge and simplify the plan of chemical science, and lead to a correct miner- 

 alogical system." This aim was again clearly defined in a communication to the French 

 Academy of Sciences in 1863, published in the Compte Rendu and also, in a translation 

 by the author, in the American Journal of Science, in the same year. ' Therein, while 

 adverting to an earlier note on the same subject, which appeared in the Compte Rendu for 

 July 9th, 1855, it was said that the views of polymerism in mineral species and of the con- 

 nection between relative condensation or specific gravity, hardness, and chemical characters 

 are "as I have already elsewhere shown, of great importance in mineralogy, and will form 

 the basis of a new system of classification which will be at the same time chemical and 

 natural-historical." These early papers however, perhaps from the general and abstract 

 manner in which the subjects were then treated, have hitherto received but little atten- 

 tion either from chemists or from mineralogists. 



§ 11. The whole subject was again discussed in ISfiY in an essay entitled " The Objects 

 and Method of Mineralogy," in which the argument of the preceding papers was resumed. 



Compte Rendu ile I'Acad., .Tune 29, 1863, and Amor. Jour. Science, xxxvi. 420-428. 



