244 On the Composition of Arragonite. [Oct. 



made, in order to detect in it some constituent which does not 

 exist in calcareous spar. But the attempts of Klaproth, Vauquelin, 

 Fourcroy, Bucholz, Chenevix, Thenard, and Biot, were all unsuc- 

 cessful ; and these skilful analysts were obliged to conclude that its 

 constituents are the very same with those of calcareous spar. 

 About a year ago, a new analysis of arragonite, by Mr. Holme, was 

 read to the Linnaean Society. He found, as had indeed been ob- 

 served before, that it contained nearly ] per cent, of water. He 

 therefore considered it as a hydrate, and ascribed the peculiar pro- 

 perties of arragonite to the water which it contained. In a former 

 number of the Annals of Philosophy, I mentioned that Stromeyer, 

 Professor of Chemistry at Gottingen, had announced the existence 

 of strontian as a constituent of arragonite. I shall now lay before 

 the English reader a translation of three papers, which are all (as far 

 as I know) that have been hitherto published in Germany on the 

 subject. The first two are by Stromeyer himself; the last is by 

 Gehlen, who repeated and verified the results of the former chemist. 

 These papers will put it in the power of Biitish chemists to deter- 

 mine how far the solution of the problem by Stromeyer may be de- 

 pended on. If any doubts exist, nothing is more easy than to put 

 them to the test of experiment. — T. 



I. 



Discovery of the true Nature of Arragonite, and the Chemical 

 Difference between it and Calcareous Spar; in a Letter from 

 Stromeyer, Professor of Chemistry in Gottingen, to Professor 

 * Gilbert* 



Gottingen, Feb. 28, 1813. 



Among various minerals, which I this winter subjected to analysis, 

 is the arragonite. It may seem surprising that I should undertake a 

 new analysis of this mineral, which has been already examined by 

 Klaproth, Vauquelin, Fourcroy, Bucholz, Thenard, and Biot. 

 These chemists considered it as pure carbonate of lime, and as 

 differing from calcareous spar neither in the nature nor proportion 

 of its constituents. But however precise and conclusive these ana- 

 lyses may appear, I must acknowledge that I entertained some 

 doubts respecting their accuracy. The structure of arragonite differs 

 so essentially from that of calcareous spar, that the two minerals 

 cannot be referred to the same species. And this is the only case 

 in which chemical analysis and the laws of crystallization are at 

 variance with each other. 



It gives me therefore much satisfaction to be able to state, that I 

 have at last ascertained an essential difference between the compo- 

 sition of arragonite and calcareous spar, which puts an end to the 

 apparent discrepancy between analysis and the laws of crystalliza- 

 tion. Arragonite, besides carbonate of lime, contains also car- 

 lonate of strontian, chemically combined with the former in a con- 



» Gilbert's Annalen der Physik, xliii. 229. March, 1813. 



4 



