1870.] Notices of Scientific Works. 83 



first year's course is only preparatory, and chiefly chemical. The 

 student first learns the properties of the elements, and thus be- 

 comes, to some extent, acquainted with the characters of such species 

 as the diamond, graphite, sulphur, and the native metals. He then 

 advances to the study of simple chemical combinations, and is thus 

 made acquainted with the chief acids and metallic oxides. This 

 chemical course occupies a summer session, and is followed, during 

 the succeeding winter course, by the study of the physical pro- 

 perties of minerals, as demonstrated on certain species of simple 

 composition. Our author's mode of teaching may be illustrated 

 by an example of his lesson on Quartz. A piece of common 

 quartz is exhibited to the class, pulverized, and treated successively 

 with water and the ordinary acids, for the purpose of showing its 

 insolubility in these reagents. A small quantity is then mixed 

 with an alkaline carbonate, and slowly heated for a quarter of an 

 hour in an iron capsule. The effervescence consequent on the 

 expulsion of the carbonic gas points to the acid character of 

 silica; while the formation of a vitreous silicate illustrates the 

 chemical composition of glass. During these experiments, an apt 

 teacher will, of course, entertain his class by a valuable lesson on 

 the manufacture of glass, and by explaining the method pursued 

 in the analysis of siliceous minerals. Having thus become familiar 

 with the chemical characters of the species, a well-formed piece of 

 rock-crystal is exhibited to illustrate its crystalline form. The six- 

 sided prism and its two terminal pyramids furnish a text for much 

 instruction on the crystallography of the hexagonal system, whilst 

 models of the forms are made in clay before the class, or, still 

 better, by the students themselves. Attention is then directed to 

 the other physical properties of quartz : its hardness is shown by 

 its resistance to the knife, and by striking sparks with steel ; its 

 specific gravity is taken; its phosphorescence exhibited; and 

 electricity is developed by friction. In this way the student be- 

 comes interested in chemical and physical science ; and if no other 

 scientific study be introduced into a system of general education, 

 much solid instruction can be imparted by a judicious study of our 

 common minerals. 



The second year's course comprehends work of a more strictly 

 scientific character, and includes the principles of classification and 

 a description of the more important mineralogical species. 



To supply a work adapted for instruction of this practical kind, 

 Dr. Senft has prepared a useful Text-book of Mineralogy and 

 Lithology. The first part is devoted to the general principles of 

 mineralogy ; the second, to a description of the principal species ; 

 and the third, to the study of rocks or aggregates of minerals. In 

 the notice of species those only are described which have acquired 

 importance by their wide distribution, by their applications in the 



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