CH. VII MICRO-METALLOGRAPHY 159 



A. F. W. Auleitung, etc. Jena, 1900. Hugh Gait, — The Microscopy 

 of the starches, illustrated by photo-micrographs, London, 1900. 



THE MICROSCOPE IN METALLOGRAPHY 



§ 233. In the modern investigation of metals and alloys much 

 light has been thrown upon the structural peculiarities which render 

 some mixtures satisfactor3* and others unsatisfactory. There are two 

 great methods : First, that of studying fractured surfaces without re- 

 course to any reagents. Second, to polish a metallic surface carefully 

 with emery or carborundum and finally with rouge or diamantine and 

 then etch it with some acid for a longer or shorter time. For either 

 method reflected light must be used. For low powers that obtained at a 

 good window or by a lamp or a lamp and bulls eye are good. The illum- 

 inating objectives (§ 28), i. e. objectives in which a prism in the side 

 of the objective reflects light down through the lenses which act as a 

 condenser, are preferable for most work and indeed necessary if one uses 

 high powers. For special microscope see Fig. 126 A. 



Elaborate arrangements have been devised for holding the piece 

 of metal on the stage, but some beeswax, or some clay made plastic 

 with glycerin answers well. For pictures of the appearances seen 

 in studying metallic surfaces, see the journals of engineering and 

 metallurgy, especially the Metallographist, a quarterly publication 

 devoted to the study of metals with special reference to their physics 

 and micro-structure, etc. In twenty-five or more of the great metal 

 manufacturing establishments special laboratories for microscopic 

 examination and investigation have been established. This is an illus- 

 tration of what has frequently occurred — great manufacturing interests 

 have outrun the universities in the appreciation and application of 

 methods of reasearch. Fortunately, however, laboratories are already 

 springing up in connection with the universities, and probably within 

 ten 3'ears every great technical school will have its laboratory of 

 micro-metallography where students will have opportunity to perfect 

 themselves in the preparation, photography and microscopic study of 

 the metals and alloys. 



Beside the sources of information given above, see Dr. H. Ost und 

 Dr. Fr. Kolbeck, Lehrbuch der chemischen Technologie mit einem 

 Schlussabschnitt " Metallurgie." Hannover, 1901. Behrens, T. H. — 

 Das mikroskopische Gefiige der Matalle, etc. Hamburg, 1894. For 

 an excellent bibliography of 188 titles ; see the Metallographist, Vol. 

 I, 1898, and appended to the special papers in all the volumes. Also 

 in Iron Age, Jan. 27, 1898. Carpenter-Dallinger, p. 264. 



