385 Analyses of Books. [May^, 



minerals into different species or not, provided we know what 

 is not perfectly identical, and that, in the particular descrip- 

 tion of the system, we indicate the limits, and demonstrate that 

 those species may vary without end. When we strictly adhere 

 to electro-negative classification, the compounds, especially in 

 the great families, arrange themselves in so striking a manner in 

 the order of their external characters, that they could not be 

 more completely so classed even according to the system of 

 Werner, in which the analogy of the external characters is the 

 predominant principle; a circumstance which certainly must 

 materially favour the adoption of this method. 



I shall now attempt a mineralogical arrangement according to 

 the negative elements, preserving the great division of minerals 

 into two classes, one containing those of inorganic, the other 

 those of organic composition. The first comprehends eighteen 

 families, which succeed each other from the most positive to the 

 most negative, in the following order: iron, copper, bismuth, 

 silver, mercury, palladium, platina, osmium, gold, tellurium, 

 antimony, arsenic, carbon, azote, selenium, sulphur, oxygen, and 

 chlorine. The eight first are composed of only one or two 

 species ; but the rest contain a great number, and under oxygen 

 all the oxidated minerals are arranged. It has not appeared to 

 me to be useful or convenient to subdivide these eighteen fami- 

 lies, and the distinction between oxidated and non-oxidated 

 bodies follows of course. The place assigned to chlorine, which 

 comes after oxygen, is a deviation from that strict order, which 

 may be defended on the ground that chlorine expels oxygen 

 even from the strongest bases, and is itself expelled by oxygen 

 only from the weakest; and in the acids which it forms, chlorine 

 is positive with respect to oxygen, and consequently should 

 precede it. I have placed it, however, after oxygen, because 

 this last family terminates with salts, and that of chlorine is 

 almost wholly composed of salts. Should iodine be found to 

 belong to the mineral kingdom, I should place it between oxygen 

 and chlorine. 



(To be continued.) 



Article XII. 

 Analyses of Books. 



An hitroduction to the Study of the Laws of Chemical Combina- 

 tion and the Atomic Theory, drawn up for the Use of Students. 

 By Edward Turner, MD. FRSE. Lecturer on Chemistry, and 

 Fellow of the Royal College of Physicians, Edinburgh. 



The author of this compendium has executed a task for 

 which both the teacher and the tyro are indebted to hira. He 



