6 14 General Notes. [July, 



zoogeographical point of view, by Professor Studer (Berne); On 

 the progress of our knowledge of Sumatra, by Professor Kan (Am- 

 sterdam) ; On the alleged influence of the earth's rotation upon the 

 formation of river-beds, by Professor Z6ppritz (Konigsberg) ; On 

 the colonies of Germans and their neighbors in Western Europe, 

 by Herr Meitzen (Berlin); On the historical development of geo- 

 graphical instruction, by Dr. Kropatschek (Brandenburg); On 

 the treatment of subjects relating to conveyance in geographical 

 instruction, by Professor Paulitschke (Vienna) ; On the introduc- 

 tion of metrical measures in geographical instruction, by Professor 

 Wagner (Gottingen) ; On the relation between anthropology and 

 ethnology, by Professor Gerland (Strassburg); On the ethnologi- 

 cal conditions of Northern Africa, by Dr. Nachtigal (Berlin) ; On 

 the Polar question, by Professor Neumayer (Hamburg) ; On the 

 geographical distribution of Alpine lakes, by Professor Credner 

 (Greifswald) ; On the true definition of the development of coasts, 

 by Professor Giinther (Ansbach) ; On geographical instruction in 

 its relation to natural sciences, by Professor Schwalbe (Berlin); 

 On the Guldberg-Mohn theory of horizontal air currents, by Pro- 

 fessor Overbeck (Halle) ; On the systematic furtherance of the 

 scientific topography of Germany, by Herr Lehmann (Halle). 

 MICROSCOPY. 1 

 MICRO-CHEMISTRY.— In a paper by H. Reinsch on the detection 

 and separation of certain minerals under the microscope, it is 

 claimed that the use of the microscope in chemical analysis is 

 not only rapidly increasing, but that it is approaching the spec- 

 troscope and in some respects surpassing it in usefulness. It is 

 admitted, however, that great skill is required in manipulation, 

 and in preparing test objects to verify results, as appearances vary 

 according to the degree of concentration of the solutions used, 

 and different reactions will sometimes be obtained from the same 

 salt. The following are some of the more interesting experi- 

 ments, as translated in the Scientific . Xmenoni Supplement. 



"Silica, of all substances, yields the most varied and beautiful 

 forms, resembling plants and ferns, often presenting, in the most 

 glowing colors, five-leaved flower forms in infinite varieties. To 

 obtain these forms, we place a drop of a four per cent, solution of 

 potassium silicate on an object slide, and then add a drop of a 

 two per cent, solution of sodium bicarbonate, and then allow the 

 liquid to evaporate at the ordinary temperature ; after a few hours 

 have elapsed the most beautiful flower forms will be found spread 

 over the slide, and will be readily recognized by a pocket lense, 

 but when examined by the microscope with the Nicol at 90 , will 

 exhibit the crystals gleaming with a most magnificent play ot 

 colors. By moistening the object with a drop of copal varnisli, 

 and covering it with a thin glass, these forms may be permanently 



. 



! by Dr. R. II. Ward, Troy, N. Y. 



