36 jinahjt'icttl Experiments on 



rently beginning to decompose) of vellow. Its lustre i:t 

 silky ; some of the. specimens possess semi-transparency, 

 but in general it is nearly opake. Its texture is loose, but 

 small fragments possess great hardness, so as to scratch 

 agate. 



" It produces no effect on the smell when breathed upon ; 

 has no taste; does not become electrical or phosphorescent 

 by heat or friction; and does not adhere to the tongue till 

 after it has been strongly ignited. It does not decrepitate 

 before the flame of the blow-pipe; but it loses its hardness, 

 and becomes quite opake. In consequence of the minute- 

 ness of the portions in which it is found, few of them ex- 

 ceeding the size of a pea, it is very difficult to ascertain its 

 specific gravity with any precision ; but from several trials I 

 am disposed to believe that it does not exceed 2'70, that of 

 water being considered as l-'OO. 



III. Chemical Characters of the Fossil. 



The perfect^}' white and semi-transparent specimens of 

 the fossil arc solubk both in the mineral acids and in fixed 

 alkaline lixivia by heat, without sensiblv effervescing, and 

 without leaving any notable residuum ; but a small part re- 

 mains undissolved when coloured or opake speclmeng are 

 exposed to the alkaline lixivia. 



A small semi-tranijparent piece, acted on by the highest 

 heat of an execUent forge, had its crystalline texture de- 

 stroyed, and was rendered opake; but it did not enter into 

 fusion. After the experiment it adhered strongly to the 

 tongue, and was found to have lost more than a fourth of 

 its weight. Water and alcohol, whether hot or cold, had 

 no eti'ect on the fossil. When it was acted on by a heat of 

 from ^11°' to 600" Fahrenheit in a glass tube it gave out an 

 elastic vapour, which, when, condensed, appeared as a clear 

 fluid possessing a slight cnipyrcuniatic smell, but no taste 

 different from that of pure water. 



The solution of the fossil in sulphuric acid, w-hcn eva- 

 porated sufliciently, deposited crystals which appea^red in 

 thin plates, and had all the properties of sulphate of alu- 

 minc ; and the solid matter, when redissolved and mixed 

 with a little carbonate of potash, slowly deposited octaedral 

 crystals of alum. The solid matter precipitated from the 

 solution of the white and semi-transparent fossil in muriatic 

 acid, was in no manner acted upon by solution of carbo- 

 nate of ammonia, and therefore it could not contain any 



glucjne 



