288 ON THE FREESTONE QUARRIES OF 



Native allum, is found on the lower projecting surfaces of the 

 rocks, where they are in wet situations, probably produced by 

 the sulphur of the pyrites combining with the clay of aggre- 

 gation. 



The colour of the stone varies from white to a dark rusty 

 tint. Herewith I present to the Society, two blocks, the one 

 of the whitest, the other of the darkest tint. The dark block 

 was, when cut, of a rusty brown, but wishing to weigh the 

 stone in its driest state, 1 placed it on the plate ol an iron stove. 

 In a quarter of an hour its colour was changed almost to black. 



The degree of hardness is very various. When moderately 

 hard, its fracture is rough and irregular, when very hard, con- 

 cave and even, when breathed upon, it has a strong earthy, 

 and somewhat hepatic smell. 



The specific gravity of the stone is as various as its colour 

 and texture. The two blocks herewith presented, are very ac- 

 curately four inches square and two inches thick. — They weigh 

 as follows: — 



The brown block 2 ft 6.69 0z Averd. 

 white block 2 3.96 



.... difference 2.7 3 0Z 



54 of these blocks make a cube foot, therefore the difference 

 of weight in one cube foot, between the white and brown 

 stone would be, 9& 3.42.°* 



The white block absorbed in 24 hours, of river water 

 6\25 0z , or at the rate of upwards of 21 ft per cubic foot. 



One of the most remarkable circumstances belonging to this 

 stone, is the arrangement of the particles of sand of which it 

 consists. In whatever direction a block is cut, the successive 

 accumulations or strata, which may be easily distinguished by 

 the different size of the grains, their colour, the admixture 

 with other substances, and their individual parallelism, appear 

 not to lie in beds parallel to each other, but in masses bound- 

 ed by wavy lines; or which are suddenly cut oft by other 

 masses, the lines of which wave in another direction; and this 

 appearance is such, that many stones exhibit by the lines of 

 their strata, a good representation of the wavy hills of the sand 

 coast, as will be seen by reference to the plate in the fourth 

 volume of the Transactions of the Society. 



