1821.] Dr. Clarke on Arragonite. 59 



much exercised the talents, exhausted the resources, and dis- 

 appointed the expectations of the most distinguished chemists 

 in Europe, as that of arragonite." Fortunately the appellation 

 bestowed upon it by Wemer, who first separated it as a distinct 

 species from lime spar, being merely borrowed from the name of 

 the Spanish province, Arragon, in which it was originally found, 

 is not likely to convey any false ideas of its chemical nature, or 

 to perpetuate the errors of those chemists whose ingenuity has 

 been hitherto baffled in their endeavours to become acquainted 

 with its constituents. Kirvvan, 27 years ago,* conjectured that 

 it contained strontian ; and Prof. Stromeyer, of Gottingen, has 

 discovered strontian in some of the sub-varieties; but it remains 

 to be proved whether strontian be an essential, or only a casual 

 constituent of arragonite. Mr. Holme, in a series of very 

 accurate and elaborate experiments upon arragonite, proved that 

 it contains a certain portion of water as essential to its chemical 

 composition; but he was unable to detect a single atom of 

 strontian .-[ In the uncertainty, therefore, still subsisting with 

 regard to its chemical nature, it will be expedient to show how- 

 much is yet known of its natural history, and what the different 

 appearances are which constitute its several sub-varieties. 



When it was first discovered, from its resemblance to chloro- 

 phane in its phosphorescence when heated, it was believed to 

 contain fluoric acid.j This opinion is noticed by Baron Born 

 in his Catalogue Raisonnee, which was published at Vienna 

 in the year 1790 ; and he cites Crell's Chemical Annals for 

 the year 1788, to show from Klaproth's analysis of arrago- 

 nite/that the opinion is erroneous. § In Baron Bom's Catalogue, 

 arragonite, for the first time, is made to class among the carbon- 

 ates of lime. He calls it " spath calcaire, prismatiqtie, violet et 

 blaric, dprisme hexaedre tronqui net, des limites entre I' Antigone et 

 Valence en Espagne." For a long time the insular hexagonal 

 crystals described by De Born, and brought from Spain, were 

 the only examples of arragonite known to mineralogists. They 

 were usually sold at very considerable prices ; sometimes as high 

 as a guinea each ; and owing to the demand, even for these, || the 

 dealers in mineralogy anxiously sought, in sales, and other places, 

 for specimens of arragonite, which they commonly denominated 

 " hard spar ; " having no other criterion than its hardness to 

 distinguish it from common lime spar, both effervescing in acids, 



* See the edition of Kirwan's Mineralogy, published in 1794. 



+ See Observations on Arragonite, together with its Analysis, by the Rev. John 

 Holme, AM. FLS. as read before the Linnean Society of London, April 6, 1813. 



* I possess a mineral exhibiting an intermediate phenomenon between common can- 

 non spar and arragonite. It cannot be converted into lime by the blowpipe. Owing 

 to its phosphorescence, and the resemblance of its crystalline form to apatite, it was 

 considered in Copenhagen as a phosphate of lime. This mineral came from Greenland. 



§ Catalogue Methodique et Raisonnee, &c. par M. de Born, torn. i. p. 321. Vienna, 

 1790. 



J| " La plupart des Cristaux isoles," says Count Bournon, " sont tres-rares."— Ca» 

 taloguc de la Collection Mineralogique, p. 10. A Londres, 1813. 



