40 The Microscope. 



of Sciences, the American Society of Microscopists and of the 

 Ro3'al Mi3roscopical Society of London. His death leaves a 

 gap in the ranli of scientific workers which can not easily be 

 filled. 



METHOD OF PREPARING AND MOUNTING MINERAL 

 SECTIONS FOR STUDY UNDER THE MICROSCOPE. 



FRED. B. KILMER. 



THE method of preparing and mounting sections of minerals 

 and rocks for microscopical work was recently illustrated 

 by Prof. Frank L. Nason, at a meeting of the New Jersey Micro- 

 scopical Society. It is the method as used in the laboratory of 

 the New Jerse}^ State Geological Survey, and contains many 

 things of interest to all microscopists ; and the methods can be 

 adapted to the demands of any who may desire to mount such 

 substances. 



The mounting of sections of rocks and minerals, though some- 

 what tedious, does not contain an}^ dilFiculties that may not be 

 surmounted by the amateur, and a section once mounted is cer- 

 tainly sometliing worth having for its beauty, when viewed by 

 plain, transmitted light, or under the polarizer. 



Then it is hardly possible, under modern methods, to gain a 

 clear idea of rock and mineral structure in any other way. 



In the survey work just mentioned, the field geologist selects 

 the specimens that ma}^ seem of interest and opposite a number 

 in his note-book careful!}- describes the surroundings and every- 

 thing that may be of service in the study of the specimen. A 

 piece somewhat larger than a hen's egg is put in a strong manilla 

 envelope, bearing the note-book number, to be sent to the Station. 

 As the collector maj'- not see his specimen again for months, 

 perhaps never, we perceive the value of his field notes and num- 

 bering. His records either accompany or follow the specimen 

 and serve as the basis of all knowledge and history connected 

 with the specimen. 



Arrived at the laboratory, it is taken from the envelope and 

 its number printed on it. A heavy glass slip is marked with 

 the same number with a diamond, and a piece is chipped ofi", 

 generally longitudinally, to obtain a section across the layers of 

 the structure. 



