I5i 



MR. DAVY's experiments 



Its fenfible cha 

 ra£lers 

 Radiated hem'if- 



it was confidered as a zeolite ; Mr. Hatchett, however, con- 

 cluded, from its geological poiition, that it rnoft probably did 

 not belong to that clafs oF ftones ; and Dr. Babington, from 

 ^^.phyfical chara6lers, and from fome experiments on its 

 folutions in acids, made at his requefl by Mr. Stocker, afcer- 

 tained that it was a mineral body, as yet not defcribed, 

 9nd that it contained a confiderable proportion of aluminous 

 earth. ,,* 



It is to Dr. Babington that I am obliged for the opportu- 

 nity of making a general invefligation of its chemical nature ; 

 and that gentleman liberally fupplied me with fpecimens for 

 analyfis, 



II. Senfihle CharaBei^s of the FoJ/il. 



The moft common appearance of the foffil is in fmall 

 hemifpherical groups of cryftals, compofed of a number af 

 pherical groups jfi'aments radiatmg from a common center, and inferted on 

 white, fi Iky, (he furface of tne fliift ; but in feme inftances it exl(is as a 

 9ious. 'colledion of irregularly difpofed prifms forming fmall veins 



in the ftone : as yet, I believe, no infulated or diftincl cryftal 

 has been found. Its colour is white, in a few cafes with a 

 tinge of ^ray or of green, and in fome pieces (apparently 

 beginning to decompofe) of yellow. Its luftre is filky ; fome 

 of the fpecimens polTefs femi-tranfparency, but in general it 

 is nearly opaque. Its texti^is loofe, but i||^all fragments 

 pofTefs great hardnefs, fo as ib fcratch agate. 



It produces no effecl on the fmell when breathed upon, has 

 no tafte, does not become electrical or plfofphorefcent by heat 

 or fricypn, and does jjot adhere to the tongue till after it has 

 been ftrongly ignited. It does not decrepitate before the flame 

 of the blow-pipe ; but it lofes its hardnefs, and becomes 

 opaque. In confeqiience of the minutenefs of the portions 

 which it is found, fevv|jf l^jem ejajj^ding the fize of a pea, it 

 is very difficult to afcertain its fpecific gravity with any pre- 

 cifion ; but from feveral trials I am difpofed to believe^ that 

 it does not exceed 2,70, that of water being confidered 

 as 1,00. ^ i, 



III. Ckepiical Charaaers pf th Fojfil 



The perteftly White and femi-titinfparen|, fpecimens of the 

 foflil are foluble both in the mine|^ acids and rn Iked alk?<^ 

 line liriivia by liopt, wit^huul fennbly cfiervelriug -.v.vX w.i|il^o^t 



leaving 



Other charac- 



Chemical habi- 

 tudes. 



Soluble in acids 

 and in f. alkaiii, 



*m 



