Mr A. Connell's Analysis ofGmelinite or Hydrolite. 361 

 Ivsed some time previously by Vauquelin, with the following 



100. 98.50 



Some time ago Mr Rose, mineral dealer of this city, was so 

 food as to give me a very fine specimen of Gmelinite from 

 the county of Antrim in Ireland, for the purpose of being sub- 

 jected to a chemical examination, -f- 



The specimen was in fine crystals of considerable size, and 

 possessing the usual form of a very short six-sided prism ter- 

 minated at both extremities by a six-sided pyramid. The trun- 

 cation of the apex was only occasionally observable. The crys- 

 tals were of great purity, being white and semitransparent, 

 whilst in many Irish specimens they are reddish, and scarcely 

 translucent. The prism was streaked horizontally, and the 

 pyramid parallel to its own terminal edges, in the manner 

 shewn by Haidinger's figure of the crystal, X although less dis- 

 tinctly. It may be proper to notice, that I could scarcely ob- 

 serve the quality stated by Sir David Brewster, of bristling up 

 and scaling off when approached to the flame of a candle ; al- 

 though I noticed it in a reddish and somewhat opaque specimen 

 of Irish gmelinite. 



(a) 17.67 grains of the crystals reduced to impalpable pow- 

 der, were decomposed by muriatic acid. The silica separated 

 as usual, weighed, after ignition, 8.97 grains. It was dissolved 

 in boiling potash ley, and left a little imperfectly decomposed 

 mineral, from the silica of which, .45 of alumina and .059 of lime 

 were separated by fusion with carbonate of soda and other neces- 

 sary steps. The proper amount of silica was thus 8.461 grains. 



" Ed. Jour. Science, ii. 262. 



t The Irish variety of this mineral was analysed, a few years ago, by Dr 

 Thomson, but the quantity operated on was only 5.3 grains, which were 

 decomposed by carbonate of barytes ; and the result differed considerably 

 from that of Vauquelin. Trans. Roy. Soc. Ed. xi. 448. 



X Mohs' Mineralogy^ fig. 195. 



