THE 



LONDON AND EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



JUNE 1838. 



LXXII. On iheFmination of Calc Spar and Arragonite. By 

 GusTAVE Rose.* 



'T'HAT calc spar and arragonite, notwithstanding their dif- 

 ferent crystaUine form, have the same chemical composi- 

 tion, and are therefore heteromorphous or isomeric bodies, has 

 long since been acknowledged, and will now, by the following 

 experiments, be placed beyond all doubt; but the conditions 

 under which these substances are formed were hitherto quite 

 unknown. From all former observations it even appeared as if 

 both originated under very similar circumstances, as they are 

 both apparently formed in the humid as well as in the dry 

 wayf. The circumstance, however, that the stalactite which 

 is still deposited in calcareous caverns, is calc spar, while 

 the Sprudelstein of Karlsbad is arragonite, brought to my 

 mind the thought that the origin of calc spar and arragonite 

 was owing to an action of the different temperatures at which 

 the crystals of carbonate of lime are formed, and caused me 

 to make a few experiments in order to explain this subject. 



1. Crystalline Form of Carbonate of Lime in the humid way. 



If we allow a solution of carbonate of lime in carbonated 

 water to stand several weeks in an open glass at the common 

 temperature, all the carbonic acid gradually escapes, and the 

 carbonate of lime is deposited in minute microscopic crystals, 

 partly on the sides of the vessel, and partly on the surface 



* Read before the Physico-Matheniatical Class of the Academy of Sci- 

 ences of Berlin, October 16, 1837: Translated by Mr. William Francis, 

 from Pogp;endorff's Awialen, vol. xlii. p. ,353. 



+ See Poggendorflf's Annalen, vol. xxi. p. 57- 

 Phil Mag. S. 3. Vol. 12. No. 77. June 1838. 2 R 



