72 
and excellent results have been obtained in the manufacture of sap 
phires and rubies.'^ 
In 1851 De Senarmont^ obtained rhombohedrons of corundum by 
heating a solution of aluminum chloride or nitrate in a sealed tube 
to 350° C During the same year Ebelmen ^ produced hexagonal 
plates of corundum by exposing to a very high temperature in a por- 
celain kiln a platinum crucible containing one part of amorphous 
alumina and three or four parts of borax. Carbonate of soda can 
replace the borax in this preparation of corundum. By the addition 
of small quantities of different metallic oxides, various colors of 
corundum were obtained. 
In 1857 Gaudin '^ found that after heating a closed crucible con- 
taining equal parts of alum, sulphate of potash, and charcoal before 
the oxyhydrogen blowpipe corundum was one of the products of the 
reaction. 
Eisner '^ obtained red crystalline grains of corundum by fusing 
before the oxyhydrogen blowpipe anhydrous alumina with bichro- 
mate of potash. 
H. Saint-Claire Deville and Caron/ in 1858, produced magnificent 
hexagonal plates of corundum by heating to a white heat for an 
hour anhydrous aluminum fluoride in the bottom of a charcoal cruci- 
ble, suspended in the center of which was a cupel of the same mate- 
rial filled with bori<3 acid. By adding a little chromium fluoride in 
varying amounts, red, blue, or green corundum was obtained. 
In the year 1861 Debray -'^ found that corundum was formed by 
passing a slow current of chlorhydric acid over aluminate of soda at 
a red heat, or over a mixture of aluminum phosphate and lime. He 
also produced crystals of corimdum by melting phosphate of alumina 
with three or four times its weight of potassium or sodium phosphate. 
Hautefeuille,'' in 1865, produced corundum crystals by slowly pass- 
ing hydrofluoric-acid gas, previously diluted with nitrogen and steam, 
over amorphous alumina heated to a bright red in a platinum tube. 
" Bourgeois, L., Reproduction artificielle des roineraux : Encyclopedie chimique, vol. 2 ; 
Kunz, G. F., On ttie new artificial rubies : Trans. New York Acad. Sci., October 4, 1886. 
" Comptes rendus, Acad. Sci., Paris, vol. 32, 1851, p. 762; L'Institut (I'aris), 1851, j). 
165; Annalen Cliom. und Pharm., vol. 80, p. 214; Pharm. Centralbl., 1851, p. 518. 
*• Annales de chim. et de pbys., 1851, vol. 33, p. 34. 
" Comptes rendus, Acad. Sci., Paris, vol. 44, p. 999 ; L'Institut, 1857, p. 110 ; .Tour 
Prakt. Chem., vol. 70, p. 381 ; Bull. TTniv. de Geneve, vol. 34, p. 68 ; Jahrbuch fiir Mine- 
ral., 1857, p. 444. 
« Jour. Prakt. Chem., vol. 17, p. 175. 
r Comptes rendus, Acad. Sci., Paris, vol. 46, 1858, p. 764 ; L'Institut, 1858, p. 133 ; 
Annalen Chem. und Pharm., vol. 108, p. 55 ; .Tour. Prakt. Chem., vol. 74, p. 157. 
«' Comptes rendus, Acad. Sci., Paris, vol. 52, 1861, p. 985; L'Institut, 1861, p. 165 ; 
Annalen Chem. und Pharm., vol. 120, p. 184; Jahrbuch fiir Mineral., 1861, p. 702; Bull. 
Soc. Chimique, 1865. 
'' Annales de chim. et de phys., vol. 4, 1865, p. 153. 
