242 Mr Haidinger's Account of the Specific Gravity 



27. Natrolite, the fibrous mass near the centres of the globular 

 masses of this same variety, 2.152 



28. Chabasie, the rhombohedron R, from Giants Causeway, 2.041 



29. Chabasie, from the same locality, in crystals, presenting all 



the rhombohedrons known in the species, and several pyramids, 2.043 



30. Chabasie, also from Giant's Causeway, in compound groups, 

 apparently traversed by a great number of fissures, 2-005 



The specific gravity of the crystals from Bohemia has been 

 found = 2.100 by Professor Mohs. Chabasie forms a curious 

 instance of the dangers of authority in science. The num- 

 bers 2.1 176, given by La Metherie* and Fourcroy,-f- differ but 

 little from those obtained by Mr Mohs and myself. But we 

 find in the first edition of Hauy's Mineralogy,^ the numbers 

 2-7176 evidently agreeing with those of La Metherie and 

 Fourcroy, with the difference only that the second decimal is 

 changed. In the works subsequent to this period, the autho- 

 rity of Hairy has been preferred to the former correct deter- 

 mination, and 2.7, sometimes along with the rest of the deci- 

 mals, are given by Lucas, a Brongniart, b Thomson, Karsten, d 

 Steffens,' Hoffmann f Hausmann,& Oken, h Cleaveland,' Jame- 

 son,' Leonhard," Ure, 1 Phillips," 1 Beudant, n and probably by 

 many others, the works of which I have not had an opportu- 

 nity of consulting. As the characteristic of Mohs, which ap- 

 peared in 1820, contained a new and correct indication of this 

 property, Professor Jameson has quoted it along with the 

 erroneous specific gravity of Hatiy, in the third edition of his 

 system, and the limits 2.0 — 2.71, given by Leonhard like- 

 wise, include the true specific gravity. 



31. Siilbite, thick prisims, from Iceland, 2.161 



32. Heulandite, a large single crystal, from Iceland, 2.192 



33. Heulandite, smaller crystals, from Iceland, 2.213 



* Theorie de (a Terre- t. iii. p. 313. 1797. t Systeme des Connoissan - 

 ces Chimiqn.es. t. ii. p. 312. 1800. X Traiti t. iii. p. 176. 1801. 



a Tableau Methodique. 1806. t. i. p. 70- b Traiti elem. de Min- 1807. 

 1. 1. p. 382. c System of Chem. 3d ed- 1807. vol. iv. p. 318. d Mineral. 

 Tabel. 1808. s. 31. ' Voblst. Handb. der Oryctogn. 1811. th. i- s. 400. 

 'Handb. der Min. 1812. tb. ii. s. 259. « Handb. der. Min. 1813. th. ii. 

 s. 585. h Lehrb. der Min. 1813. th. i. s. 349- ! Elem. Treatise on Min. 

 1816- p. 315. ' System of Min. 3d ed. 1820. vol. i. p. 360. k Handb. der 

 Oryctogn. 1821. p. 450. ' Diet, of Chemistry. 1821. m Elem. lntrod. to 

 Min. 1823. p. 139. " Traite elem. de Min. 1824. p. 351. 



