011 



COR 



Madras, in * rocky matrix of considera- 

 ble hardness, partaking- of the nature of 

 the stone itself. It occurs also in China, 

 and in Ceylon, Ava, &c. The Count de 

 Bournon pointed out the resemblance be- 

 tween this mineral and the sapphire, in a 

 dissertation published by him and Mr. 

 Greville in the Philosophical Transac- 

 tions for 1798, and suggested it as proba- 

 ble, that corundum may be only a variety 

 of the sapphire ; and that the seeming- 

 difference in their ingredients is owing 1 to 

 the impurity of those specimens of corun- 

 dum, which have hitherto been brought to 

 Europe. This conjecture has been since 

 confirmed by a subsequent dissertation of 

 Bournon, and the chemical analysis of 

 Chenevix. Werner subdivides it into two 

 species, namely, corundum, and adaman- 

 tine spar ; but, in reality, they seem to be 

 only varieties, or, at most, subspecies of 

 the same species. The chief difference 

 exists in the colours. 



Corundum has been found in India, in 

 the Carnatic, and on the coast of Malabar. 

 It occurs massive, in rolled pieces, and 

 ci-ystallized ; crystals the same as in sap- 

 phire ; colour greenish-white, passing 1 in- 

 to greenish-grey, and asparagus-green, 

 sometimes pearl grey, which passes into 

 flesh-red; surface rough; fracture foli- 

 ated ; specific gravity 3.7 to 4.2. 



Mr. Chenevix obtained the following 

 constituents from the specimens of the 

 corundums, which he subjected to chemi- 

 cal analysis. 



Silica . 

 Alumina 

 Iron 



Loss 



IMPERFECT CORUNDUM. 



From the From From From 



Carnatic. Malabar. China. Ava. 



. . 5.0 7.0 5.25 6.5 



. .91.0 86.5 86.50 87.0 



. .1.5 4.0 6.50 4.5 



97.5 97.5 98.25 98.0 



,' y 2.5 2.5 1.75 2.0 



100 100 100 100 



PERFECT CORUNDUM. 



Blue, or Red, or 



Sapphire. Oriental Ruby. 



Silica . . . 5.25 7.0 



Alumina . 92.00 90.0 



Iron . . 1.00 1.2 



Loss 



VOL. IV 



98.2 

 1.8 

 100 



CORUSCATION, a glittering, orgleam 

 of light issuing from any thing. It is 

 chiefly used for a flash of lightning dart- 

 ing from the clouds in time of thunder. 

 See METEOROLOGY. 



CORYLUS, in botany, English hasel, 

 or nut-tree, a genus of the Monoecia 

 Polyandria class and order. Natural or-, 

 der of Amentacese. Essential character : 

 male calyx one-leaved, three-cleft, scale- 

 form, one-flowered; corolla none; sta- 

 mens eight. Female calyx two-leaved, 

 lacerated; corolla none; styles two; nut 

 ovate. There are three species, with ma- 

 ny varieties; C. avellana, common hasel 

 nut tree, is properly a shrub, the trunk 

 of which is covered with a whitish cloven 

 bark, which is smooth on the branches, 

 frequently of a bay colour, spotted with 

 white ; the shoots are sometimes hairy, 

 ash-coloured, and green, with white tu- 

 bercles. The male catkins appear in au- 

 tumn, and wait for the expansion of the 

 female germs in spring; 'the styles are of 

 a bright red colour, long, and cetaceous ; 

 the flowering branches, especially those 

 which bear the fertile flowers, are set 

 with short fine hairs, terminating in glo- 

 bules ; the catkins are in pairs, and of a 

 yellowish-green colour. 



CORYMBIUM, in botany, a genus of 

 the Syngesia Monogamia class and order. 

 Natural order of Composite Discoidese. 

 Cinarocephalae, Jussieu. Essential cha- 

 racter: calyx two-leaved, one-flowered, 

 prismatic ; corolla one-petalled, regular; 

 seed one, below the corolla woolly. There 

 are four species, all natives of the Cape 

 of Good Hope. 



CORYNOCARPUS, in botany, a genus 

 of the Pentandria Monogynia class and or- 

 der. Natural orderof Berberides, Jussieu. 

 Essential character : nectaries five, petal- 

 shaped, alternate with the petals, glandu- 

 lousatthe base. One species, found at 

 New Zealand. 



CORYPHA, in botany, appendix palms. 

 Natural order of Palms. Essential cha- 

 racter ; flowers hermaphrodite, six- 

 stamened : spathe many-leaved ; corolla 

 three-petalled; pistil one; berry globose, 

 superior, one-seeded; seed bony, globose. 

 There are two species, viz. C. umbracu- 

 lifera, great fan palm, and C. minor ; the 

 former of which we shall give a short de- 

 scription of. It scarcely flowers till it is 

 between 30 and 40 years old. Knox de- 

 scribes the great fan palm under the name 

 of tallipot; he says it is as large as a 

 Chip's mast, and very straight. The leaves 

 are of great use, one being so broad and 

 large that it will cover 15 or 20 men ; 



K 



