112 On Solutions of Silcx in the Cavities of Minerals. 



as to form a pulpy or gelatinous mass, very soft and impressible ; this 

 mass was also soon dried by the intense heat of the weather. As there 

 was less fluid to evaporate, so, as might have been expected, there were 

 but few crystals formed ; still, they shot, here and there, as in the other 

 cavity. The spongy mass in the cavity of the larger stone admits a knife 

 to penetrate it more than an inch, and portions of its surface have a ma-f 

 miliary and stalactitical appearance. It is silex, like the other. In many 

 other pebbles cavities have been observed, some lined with the spongy 

 silicious deposites, intermixed with minute prismatic crystals,which have, 

 however, rather more lustre than those which were so rapidly formed ; 

 and the stone forming most of the immediate walls of the interior 

 of the cavities is of an opaque enamel, white as if it had been penetrated 

 by a fluid, and in some measure softened by incipient solution. In a few 

 cavities, the silicious matter had concreted into well- characterized ma-* 

 miliary chalcedony." 



The next fact mentioned by Professor Siiliman is not less 

 interesting than the preceding, and was communicated to 

 him by Mr. Eli Whitney of Newhaven, who saw the specl? 

 mens alluded to in Georgia in 1806. 



" In clearing a mill-dam, built on a solid mass of agate, (a silicious 

 stone, consisting of a mixture of jasper, hornstone, quartz, and chalce- 

 dony,) the workmen discovered a great number of hollow balls in their 

 form resembling bomb-shells. Some of them were as large as a man's 

 head, and some even eight or nine inches in diameter. When broken 

 they proved to be mere shells, the walls of which were from five-eights 

 to three-fourths of an inch in diameter, and the capacity of the cavity 

 was from a pint to two quarts or more. This cavity was filed with a 

 milky fluid, so nearly resembling white paint or white wat>h, that it was 

 used to whiten the fire places and the walls of the rooms of the neigh- 

 bouring houses. 



The next fact quoted by our author is from Bournon's 

 Mineralogy, vol. ii. p. 33, and which relates to a cavity con- 

 taining water, and which, after the evaporation of the water, 

 contained a spongy, crystalline, amorphous mass of carbonate 

 of lime. The learned editor has omitted to cite a still more 

 remarkable case of a group of regular crystals of carbonate 

 of lime, discovered by Dr. Brewster in a cavity of a quartz 

 crystal from Quebec, in the cabinet of Mr. Allan, one of the 

 most curious specimens of the kind that has perhaps ever 

 been seen. This specimen is fully described in the Editu 

 burgh Transactions, vol. x. p. 29. 



