OBSERVATIONS, 



CHIEFLY CHEMICAL, 



OK THB 



NATURE OF THE ROCK STRATA, 



IN 



i^anci^estev ants its Vitimt^. 



BY JOHN DALTON, F. R. S., &c. 



(Read December 28tb, 1827.) 



JlIaVING lately had occasion to examine some 

 specimens of the rocks in the neighbourhood of 

 Manchester, and some of the mineral and fossil 

 productions, as far as regards their chemical 

 constitution, I thought it might be, at least, of 

 some local interest, to make known the results. 



1. Colly hurst Sand-Stone. 



The colour of the rock at the top, is of a pink 

 hue-, but, at the bottom, or at 30 or 40 feet 

 below the surface, it becomes a yellow drab. 

 The specific gravity of the bottom rock, I found 

 to be 2.58 (water being 1). That of the middle 



