452 THE POPULAR SCIENCE MONTHLY. 



CORUNDUM. 



WITHIN the past two years, the attention of the scientific world, 

 especially, has been directed to the above mineral, from the 

 fact of its discovery, in place, in this country. A number of commu- 

 nications on the subject have been published by prominent men, the 

 most important of which are those from Profs. Genth and Lesley, of 

 the University of Pennsylvania ; Prof. Charles U. Shepard, of Amherst 

 College ; Dr. A. C. Hamlin, of Bangor ; and Dr. J. Lawrence Smith, of 

 Kentucky. These papers are mostly of value to men of scientific pur- 

 suits. Our readers will be interested in more* detailafl information as 

 to this mineral, and the locality where first in the history of the world 

 it is legitimately mined. 



Although corundum has been in use, as an abrasive, from an early 

 age, and under various names, it was not until near the commence- 

 ment of the present century that its localities were found and examined 

 by scholars, and its true place in mineralogy determined. For thou- 

 sands of years the Chinese had used it, under the name of adaman- 

 tine spar ; the Persians, as Armenian whetsone ; the Hindoos, as 

 corundum ; and the Egyptians, as the iron-stone of the Red Sea. 

 The natives of these countries had gathered it from the beds of 

 mountain-torrents, or in the alluvium of the valleys, after the annual 

 rains had washed it down, freeing it, in the transit, from its associate 

 minerals and impurities ; but no attempt at its legitimate mining had 

 ever been made until within the past two years, in the United States, 

 in the State of North Carolina. The mineral, from whatever locality it 

 comes, is now known in science and commerce as corundum — the name 

 given it by the Hindoos, and meaning cinnamon-stone, from the re- 

 semblance in color to that article, of the variety found in their coun- 

 try. It is pure crystallized clay or alumina, and is the next hardest 

 substance in Nature to the diamond, reducing to powder all sub- 

 stances save that gem. 



Until the researches of Haliy, the distinguished French savant, 

 about the commencement of this century, the three forms of alumina, 

 known as sapphire, corundum, and emery, were supposed to be dis- 

 tinct species. His analysis made them three varieties of one species ; 

 a decision confirmed by chemists since, and now universally accepted. 

 The earliest extended reference to corundum, of any value to science 

 or trade, appears in a joint paper by Count Bournon, of Paris, and 

 Sir Charles Greville, of London, prepared for the Royal Historical 

 Society of London, in 1798; which was soon followed by a more 

 careful mineralogical treatise, by the first-named scientist, prepared 

 by him for the same society. Sir Charles Greville's observations were 



