VIEWS ON MINERAL SPECIES. 437 



the composition of a mineral, and their mutual relations, are 

 constant, though the mineral may be produced in nature or 

 artificially in a thousand different ways. 



DANA'S SYSTEM. 



The very existence, however, of the systems discussed 

 above, and they are only a few out of many, if it signifies 

 anything, surely indicates a state of unrest, a feeling of 

 dissatisfaction with the orthodox views, if there be such. 

 We must then proceed to consider the general principle at 

 present current among mineralogists as embodied in the last 

 edition of Dana's Mineralogy, and the manner in which it 

 has won acceptance since the date of the third edition 

 (1850), when the Natural System was abandoned. 



In that volume minerals were grouped together as 

 (1) Elements, (2) Haloids, (3) Silicates, Aluminates, etc., 

 (4) Metals and metallic ores ; the minerals in each group 

 being arranged according to their metal. This plan, of 

 course, again separated such minerals as Apatite and 

 Pyromorphite, which are closely allied, and was destined to 

 be replaced by some arrangement in which the compounds 

 of each metal are not classed together but are distributed 

 into groups according to their natural affinities. 



The present edition classes minerals roughly as follows : — 

 I. Elements. 

 II. Sulphides (tellurides, etc.) (a) of semi-metals. 



(b) of metals. 



III. Sulpho-salts. 



IV. Haloids. 



V. Oxides : — (a) -of silicon. - 



(b) of semi-metals. 



(c) of metals. 



VI. Oxygen salts: — (1) Carbonates, (a) anhydrous, (b) acid, basic, 



and hydrous. 



(2) Silicates (and titanates), (a) anhydrous (b) 



hydrous. 



(3) Niobates, etc. 

 (4)]Phosphates, arsenates, etc. 



(5) Borates. 



(6) Sulphates, etc., (a) anhydrous, (b) acid, basic, 



and hydrous. 



(7) Tungstates, etc. 

 VII. Organic compounds. 



