On the Composition of Zeolite. 31 



bodies as of the same species ; because zeolite, he says, 

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



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

 be zeolites, which I had collected in the island of Staffa, 

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

 phuric acid ; and I have since repeatedly ascertained the 

 presence of the same principle in similar stones from various 

 other places; and Dr. Hutton and Dr. Kennedy had like- 

 wise detected soda in bodies, to which they gave the name 

 of zeolite. 



There was, however, no certainty that the subjects of any 

 of these experiments were of the same nature as what Mr. 

 Vauquelin had examined, or were of that species which Mr. 

 liaiiy calls mesotype. 



Mr. Haiiy was so obliging as to send me lately some 

 specimens of minerals. There hap]5ened to be amongst 

 them a cluster of zeolite in rectangular tetrahedral prisms, 

 terminated by obtuse tetrahedral pyramids whose faces co- 

 incided with those of the prism. These crystals were of a 

 considerable size, and perfectly homooeneous, and labelled 

 by himself '^ Mesotype pyramidce dit depart, du Piiy de 

 Dome." I availed myself of this very favourable oppor- 

 tunity, to ascertain whether the mesotype of Mr. Haiiy 

 and natrolite, did or did not differ in their composition, and 

 the results of the experiments have been entirely unfavour- 

 able to their separation, as the following account of them 

 will show. 



Ttn grains of this zeolite being kept red hot lor five mi- 

 nutes last 0-75 grains, and became opake and friable. In 

 a second experiment, ten grains being exposed for ten mi- 

 nutes to a stronger fire, lost 0'95 grains, and consolidatetl 

 into a hard transparent stale. 



Ten grains of this zfolile, which had not been heated, 

 were reduced to a fine powder, and diluted omriatic acid 

 poured upon it. On standing some hours, without any 

 application of heat, the zeolite entirely dissolved, and some 

 hours after, the solution became a jelly: this jelly wa:> eva- 

 porated to a dry state, and then made red hot. 



Water was repeatedly poured on to this ignited matter 

 till nothing more could be extracted from, it. This solution 

 was trently evaporated to a dry state, and this residuum 

 made" slightly red hot. It then weighed 313 grains. It 

 was muriate of soda. 



'J'he solution of this muriate of soda being tried with so- 



• Journal des Mines, No. c'. Juia 1310, p. 458. 



]uti(in« 



