1 896.J MICROSCOPICAL JOURNAL. 301 



I poured a quantity of thti carbon dust on the emery 

 plate and added some water and selected a piece of 

 granite to test its cutting qualities, finding that tlie gran- 

 ite was quickly abraded. 



I next tested it with a specimen of flint, and found 

 that the results were as remarkable as with the granite. 

 I next ascertained that the same dust would also give a 

 finished mirrored polish to the flint and granite speci- 

 mens. After having ascertained the feasibility of the 

 material, I immediately secured specimens of all of the 

 various kinds of hard minerals, such as are brought into 

 any maritime port, as ballast from other distant ports, 

 and testing them rapidly in succession, I found that all 

 known accessible rock specimens were tractable to this 

 treatment, and as a result of these experimental tests 

 and trials I was enabled to study several varieties of the 

 granitic rocks, serpentine, copper, iron and nickel slags; 

 glass, flints, agates, basalt, porphry, carborundum wheels; 

 trachytes, cherts, the silicified fossiliferous pebbles, and 

 silicified woods peculiar to the sub-carboniferous forma- 

 tions of Alabama; the hematite ores, silicified vertebral 

 bones, phosphatic flints of Florida; the various metals as 

 iron and steel, etc., so that I then realized that this 

 simple analytical method might be practically applied 

 to the study of all minerals and metals with the possible 

 exception of the diamond itself. During a part of these 

 initial experiences I used as a grinding or polishing sup- 

 port one of the squared, tempered steel plates used in 

 the chalk engraving process, and found that the polishing 

 power of the material had turned the steel plates into a 

 perfectly reflecting face mirror. In the internal struc- 

 ture of flints as polished by the means noted herein, one 

 may note the large variety of organic remains, as for- 

 aminifera, radiolarian like forms, sponge spicules, retic- 

 ulated spongy structures, Zanthidian and other bodies. 



