ADA 



that from the coafi. of Coromandcl is of a foliated texture, 

 and feems in fail to be confuftdly ciyftallized, but its Ip. 

 gr. is only 2. 785. 



Adamantine fpar is ufed throughout India and China for 

 the purpofc of polilhing fteel and gems, for wliich its great 

 hardnefs renders it pecuharly well adapted. Of the mines 

 of this (lone, and the method of proecring it in China and 

 Bengal we have no account, but fome intcrefting topo- 

 graphical information refpeiling the conmdum of the coaft 

 was procured by Mr. Grtville in 1792. In the Myiore 

 countiy, about four miles fouth of the river Cavery not far 

 from Caranel, is an excavation from i\\ to (ixteen feet deep, 

 running eaft and well about a mile and a half in the direc- 

 tion oT a vein of adamantine fpar that traverfes a hill of 

 grittv granite. The matrix of th.e vein co:iiifts of granitic 

 fragments cemented by corundum ; mafies of this, weighmg 

 fcveral pounds, are cut out with iron crows, and then 

 broken to pieces, among which the ciyllals of corundum are 

 found : thefe are loaded on horfes and bullocks, and diftri- 

 buted to the call of likuldars or polimers thvoughout Ir.dia; 

 its price, at Madras, is about fix (hillings a pound. 



This mineral appears to have been fiill brought into 

 Europe by Mr. Bulkley, a correfpoiident of Dr. Woodward, 

 wiio, in his catalogue of foreign foiTils, pv.blilhed about 17 19, 



'is found in 



ADA 



earth, or a new fimple earth with peculiar properties. In 

 this llate of the inquiiy Mr. Kirwan, and feveral other emi- 

 nent cbemiils, were induced to confider the adamantine fpar 

 as containing an earthy?// gtnerls, which was called the ada- 

 matilini; or corundum earth. Soon after Klaproth, having 

 improved his method of analyfis by the ufe of caullic pot- 

 alh as a fc^lvent, undertook a fecond time the analyfis of this 

 uncommonly refra£lo)-y foflil in which he complcatly fuc- 

 ceedcd, reducing the fuppofed adamantine earth to aiuraine 

 and filex. 



The Chinefe fpar yielded 



Alumine - - - - 84 . 



Oxyd of iron - - - 7.5 



bilex ----- 6.5 



corivtiUiUm 



has the following notices : " Nella 

 fields where the rice grows ; it is commonly thrown up by 

 ficld-rats, and ufed as we do emery, to polifii iron." — 

 " Telia convindum. Fort St. George, Mr. Bulkley. It is a 

 talky fpar, grey with a call of green ; it is ufed to polifh 

 rubies and diamonds." In Dr. Woodward's additional ca- 

 talogue of foreign foflils, 1 725. " Nella corhnndum is 

 found by digging at the foot of hills about five hundred 

 miles to the i'outhward of this place. They ufe it as emery 

 to clean arms, &c. it ferves alfo to grind rubies by making 

 it like hard cement by the help of ilick lac mixed with it. 

 Eaft India. Mr. Bulkley." From this time no farther 

 infoiTnation was obtained concerning it tiU about 1767, 

 when Mr. Berry, feal engraver of Edinburgh, received from 

 Dr. Andcrfon of Madras a box of cryilals, with information 

 of their being the material ufed by the Indian lapidaries to 

 polilh ci-yilal and all gems but diamonds. They were 

 found by Mr. Berry to cut agate, cornelian, &c. but for 

 minute engraving were not equal to diamonds, in confc- 

 «juence they were laid afide as cunofitics. Dr. Black afccr- 

 tained their difference from all the known European mine- 

 rals, and their hardnefs gained for thtm the name of ada- 

 mantine fpar. In 1784, Mr. Greville obtained fpeciniens 

 from India, together with the native name corunduyr., which 

 iifcertained their identity with Dr. Woodward's fpecimens. 

 Adefcription of its external eharafters by M. de La Metherie 

 and Hauy appeared in the Journal de phyf.que for January and 

 March 1787. Its chemical compofition, however, ftill re- 

 mained unknown till Klaproth was enabled, by the hbe- 

 rality of Mr. Greville, in facrificing fome fpecimens for the 

 purpofe, to undertake its analyfis. The extreme hardnefs 

 of the adamantine fpar, rendered the firft attempt to decom- 

 pofe it imperfeft : by the ftrongeft nitro-murlatic acid, no- 

 thing was feparated but the iron, which is accidentally dif- 

 fufed through the Chinefe variety, and after this the moft 

 concentrated acids were digefted upon it in vain. Carbo- 

 nated potalli ignited together with it for two hours, was 

 perfectly ineffedlua!, and even eleven times repeated calcina- 

 tion and fufion with cau.lic foda produced cnlj' a partial 

 decompcfition. Th.e refi-Jts of the iiril analyfis were prin- 

 cipally aluminous ca'th, together with a n-iatter that ap- 

 peared to be either a mixture of ahiminous aad filiceous 



Lofs - 



That from Bengal gave 

 Alumin; - - - 

 0<yd of iron 

 Silex - - - - 



Lofs - 



98. o 



89.5 

 1 . 25 



5 • 5 



96. 25 

 3 -IS 



The Philofophical Tranfaclions for 1798 contain a valu- 

 able paper on corundum by Mr. Greville, which is the lafh 

 addition that has been m.ade to our inform?.tion on this fub- 

 jccl ; we here find the firft authentic account of the corun- 

 diuu mine in the Myiore, the charafteriilic differences be- 

 tween the Chinefe and Indian varieties, the ciyilallography 

 of the mineral by Count Bournon, and a comparifon be- 

 tween the characlers of corundum, topaz, ruby, and 



S A P P H I EL K . 



Coi-undum is faid to have been found in France, in the 

 Forez, by Count Bournon, and in Brctagne by Morveau ; 

 of thefe, however, the latter at leaft is faid by Hauy (Jour- 

 nal des Mines.) to be titanite. Perhaps a mineral found 

 by M. Rafpe at Tiree, one of the richrides, which was 

 fuppofed by him to be Jade, belongs moi e properly to ada- 

 mantine fpar ; its fpecific gravity is 3 . 049, and in hardnefs 

 it coirefponds with the matrix of corundum, that is, it will 

 fcratch glafs readily, but not rock-ciyilal. GreviUe on 

 corundum, Philof. Tranf. for 1798. Kirwan's Mineralogy, 

 vol. i. art. Adamantine Spar. — Klaproth's Analytical 

 Effays. 



ADAMANTINiE Terrx, in the Linnxan fyftem of 

 Mineralcgy, denote the lixth order of earths; which are 

 chiefly compofed of adamantine earth. To this order be- 

 longs one fpecies, which is the adamantlnus or corundum. 



ADAMARA, in Geography, a diftrift of Abyffinia, near 

 the province of Waldubba, containing feveral confiderable 

 villages, that are inhabited by Mahometans ; who by their 

 number and ftrength contribute to the fafety of the monks 

 in that part of the country. It is fo called from ytdama, 

 which in the Amharic dialect fignifies pleafant, the name of 

 an adjacent mountain. The river An-^o runs in a contigu- 

 ous valley. Bruce's Trav. vol. iii. p. 1 79. 



ADAMAS, in AJlrohgy, a name given to the m.oon. 



Adamas, in Geography, a town of Cordova in Spain, 

 fevcn leagues from Cordova, Adamas is a.'fo a river of India, 

 the fource of which Ptolemy places in Mount Uxentus, and 

 its mouth in N. lat.' 18°, 7'. and long. 142°. 4'. 



ADAMEEA, 



