42 WRITINGS OF JAMES SMITHSON. 



ON THE COMPOSITION OF ZEOLITE. 



From the Philosophical Transactions of the Royal Society of London, 

 Vol. 01, p. 171.— Read February 7, 1811. 



Mineral bodies being, in fact, native chemical preparations, 

 perfectly analogous to those of the laboratory of art, it is 

 only by chemical means, that their species can be ascer- 

 tained with any degree of certainty, especially under all the 

 variations of mechanical state and intimate admixture with 

 each other, to which they are subject. 



And accordingly, we see those methods which profess to 

 supersede the necessity of chemistry in mineralogy, and to 

 decide upon the species of it by other means than her's, 

 yet bringing an unavoidable tribute of homage to her supe- 

 rior powers, by turning to her for a solution of the difficul- 

 ties which continually arise to them, and to obtain firm 

 grounds to relinquish or adopt the conclusions to which the 

 principles they employ, lead them. 



Zeolite and natrolite have been universally admitted to 

 be species distinct from each other, from Mr. Klaproth 

 having discovered a considerable quantity of soda and no 

 lime, in the composition of the latter, while Mr. Vauquelin 

 had not found any portion of either "of the fixed alkalies, 

 but a considerable one of lime, in his analysis of zeolite.* 



The natrolite has been lately met with under a regular 

 crystalline form, and this form appears to be perfectly simi- 

 lar to that of zeolite, but Mr. IIaCy has not judged himself 

 ■warranted by this circumstance, to consider these two bodies 

 as of the same species, because zeolite, he says, " does not 

 contain an atom of soda."t 



I had many years ago found soda in what I considered to 



* Journal dos Mines, No. XLIV. 



f Journal des Minos, No. OL. Juin 1810, p. 468. 



