ON THE COMPOSITION OF ZEOLITE. \^$ 



XL 



On the Composition of Zeolite. By James Smithson, Haq. 

 F. R. S*. 



INERAL bodies being, in fdct, nafivf chemichl jprc- Species of mi- 

 parationSf perfectly analoj^ous to those of the laboratory O^" "g^erta^ed 

 art, it is only by chemical means, that their species can be only by ch»- 

 ascertained with any degree of certainty, especially under "''*"">' 

 all the variations of mechanical state and intimate admix- 

 ture with each other, to which they are subject. 



And accordingly, w« 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 hers, yet 

 bring an unavoidable tribute of homage to her superior 

 powers, by turning to her for a solution of the difficulties, 

 which continually arise to them ; and to obtain firm grounds 

 to relinquish or adopt the conclusions, to which the princi- 

 ples they employ lead them. 



Zeolite and natrolite have been universally admitted to be Zeolite and na- 

 species distinct from each other, from Mr. Klaproth having p'^sedto^bedis- 

 discovered a considerable quantity of soda and no lime, in tinct sptcies. 

 the composition of the latter, while Mr, Vauquelin had not 

 found any portion of either of the fixed alkalis, but a consi- 

 derable one of lime, in his analysis of zeolitef, 



' The natrolite has been lately met with under a regular 

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

 milar to that of zeolite ; but Mr. Haiiy has nojt judged him- 

 self warranted by this circumstance, to consi^der these two 

 i)odlies as of the same species, because zeolite, he says, 

 ** does not contain an atom of soda j." 



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

 be zeolites, which I had collected in the island of Staffa, ul^i^Jo^g '/g^j 

 having formed Glauber's salt by treating them with sulphu- 

 ric acid; and I have since repeatedly ascertained the pre- 

 sence of the same principle in similar stones from various 



* l^hif Trans, for 181 1, p. 171. f Journal des Mines, No. XLIV. 

 i journal des Mines, No. CL, Juin 1809, p. 458. 



other 



