3^^ Chemteal Analyjis of 



fmall piece of it is heated gradually with the blow-pipe, it 

 firfi: becomes white and opaque; a number of fiflures are then 

 formed, by which its bulk appears fomewhat increafed ; and 

 after the flame is made fufficiently intenfe, it melts into a glo- 

 bule of colourlefs glafs, the tranfparency of which is imperfe<Sl 

 on account of many minute an--bubbles. Although thus 

 fufible by flrong heat, yet a very low degree of ignition 

 fcarcely affe^ls it. A piece of the ftone, after having been put 

 int« a crucible, and expoled for a fhort time to a tire which 

 made it juft vifibly red-hot, was not altered in appearance, 

 and had not loft more than x'-c^h part of its weight. In a 

 temperature, however, about 20' of Wedgwood, 1 found that 

 a fragment of this zeolite became opaque, and more eafy to 

 pulverize than in its natural ftate; at 90^ it did not melt, but 

 was glazed on the furface, adhered to the crucible, and had 

 begun to fink down ; and at 120"^ melted into an imperfedt 

 glafs of a light greenifh yellow colour, deficient in tranf- 

 parency, which a6ted ftrongly on the crucible. 



In temperatures fufficiently high, it lofes from 4^ to 5 

 per cent, of its weight; but to produce this effeft, the heat 

 muft be equal at leall to 20'^ or 25" of Wedgwood. Part of 

 the volatile matter thus driven off, is carbonic acid; for the 

 zeolite, when reduced to powder, and mixed with acids, pro- 

 duces a flight effervefcence. 1 found, by three diflerent ex- 

 periments, that the lofs of weight after the eflcrvefcence was 

 about 3 per cent.; confequently, the remaining 2 or si parts 

 may be prefumed to confifl of moifture. 



This fubflance produces a jelly, as moft other zeolites do, 

 ■with the flronger ^cids. When ground to powder, and mixed 

 with the fulphuric, nitric, or muriatic acid, the niixture be- 

 comes a firm jelly in a few niinutes, provided the acids are 

 not much diluted, or ufed in too great quantity. That which 

 is formed by the a6lion of the nitric or the niuriatic acid, is 

 nearly tranfparent ; but the ftone contains fo much lime, as 

 ■will prcfently be fljown, that with the fulphuric the jelly is 

 white aud opaque, on account of the fulphate of lime which 

 ^s generated. 



The prehnite in which it was Inclofed, as already men- 

 tioned, is of a light green colour, with fome luftre, and 

 a-confiderable degree of tranfparency. It gives fire with 

 fteel, can be readily melted with the blow-pipe, and froths 

 up much before fulion. 



Having made thefe preliminary experiments refpefting the 

 general properties of the zeolite, Tfubjedted a portion of it, in 

 the next plate^ to anylylis, to aftertain of what earth* it was 



fotnpofed, 



