COB 



[ 110 ] COR 



which disk is composed of 

 florets, with regular corollas. 



A corolla with two lips is called 

 Ulabiate: when the two lips 

 present an appearance resembling 

 the mouth of an animal, the corolla 

 is called ringent. 



The petals of all corollas are 

 placed alternately with the sepals 

 of the calyx. 



COBO'LLIFLOEJS. In botany, the fourth 

 order of the class Exogens. 



COBO'NA. (Lat.) In botany, an 

 appendage of the corolla or peri- 

 anth. 



CO'BONXUD. See Coracoid. 



CoBo'injLA. A regular subrotund, or 

 subconical shell, divided into 

 twelve areas, with an opening both 

 in the superior and inferior part ; 

 that in the superior closed by a 

 four-valved operculum. 



CO'BONATED. (coronatus, Lat.) In 

 conchology, crowned, or girt 

 towards the apex, with a single row 

 of eminences. 



CO'BPUSCLE. j (corpusculum, Lat. 



CoEPifscuLE. ) corpuscule, Fr. 

 corpuscolo, It.) A minute particle 

 of a body ; an atom. 



COBT/KDUM. (The Korund and 

 Demant-spath of "Werner : the 

 Corindon-harmophane of Hatty : 

 Corindon adamantin of Brongniart : 

 Adamantine spar of Kirwan.) A 

 genus of gems comprising four 

 species. 



1. Spinel, or dodecahedral cor- 

 undum. 



2. Automolite, or octahedral cor- 

 undum. 



3. Sapphire, or rhombohedral cor- 

 undum. 



4. Chrysoberyl, or prismatic cor- 

 undum. 



These will ail be described under 

 their several names. 



Some mineralogists constitute 

 corundum a species comprising 

 sapphire, corundum - stone, and 

 emery; others place corundum 



amongst the members of the ruby 

 family, while some consider it to 

 be a sub-species of sapphire. The 

 colour of corundum is greenish- 

 white, sometimes nearly colourless, 

 passing into greenish-grey, occa- 

 sionally reddish; sometimes it 

 possesses a Berlin or azure blue, at 

 others it is of a cochineal or crim- 

 son red. Its colours are usually 

 weakened by exposure to heat. 

 Before the common blow-pipe it 

 does not yield but with borax, 

 but before the compound blow- 

 pipe, it fuses into a grey globule. 

 The form of the primitive of 

 corundum is a slightly acute rhom- 

 boid. It occurs in crystals as 

 well as in amorphous masses of a 

 moderate size, sometimes rolled. 

 Lustre of the cross fracture shining 

 and glistening. Fracture perfect, 

 foliated, with a four-fold cleavage. 

 Its infusibility and hardness serve 

 to distinguish it from all minerals 

 which it resembles in its external 

 characters. Specific gravity from 

 3-710 to 3-873. It consists of 

 alumina 91, silica 5, iron 1-5. 

 Corundum is found in India, 

 Malabar, the Carnatic, and other 

 eastern parts, and in Italy. It 

 occurs imbedded in primary rocks, 

 having scales of mica and felspar 

 frequently adhering to its surface. 

 It is employed in polishing gems 

 and other hard substances. 



CO'BYMB. (corymbe, Fr. corymlm Lat.) 

 A kind of efflorescence. A raceme. 

 A spike of flowers, whose partial 

 peduncles take their rise from 

 different heights upon the common 

 stalk, but the lower peduncles being 

 longer than the upper ones, they 

 all form nearly a level surface at 

 the top. 



COYY'HBIATED. Garnished with bun- 

 ches of berries or blossoms, in the 

 form of corymbs. 



COBYMBI'FEBOTJS. (from corymlus and 

 feroj Lat.) Bearing berries or 

 blossoms in the form of corymbs. 



