5 & (ECONOMY 
rations of the fea, and lakes, and the vehe- 
mence of the waves, excited by turbulent 
winds pulverife ft ones, as evidently appears by 
their roundnefs along the fhore. Nay as the 
poet fays, 
The hardeft (tone infenfibly gives way 
To the foft drops, that frequent on it play. 
So that we ought not to wonder, that thefe 
very hard bodies moulder away into powder, 
and are obnoxious like others to the conform- 
ing tooth of time. 
Sand is formed of freeflow , which is de~ 
ftroyed partly by froft, making it friable, 
partly by the agitation of water, and waves ; 
which eafily wear away, difiblve, and reduce 
into minute particles, what the froft had made 
friable. 
Chalk is formed of rough marble , which the 
air, the fun, and the winds have difiblved, as 
appears by Iter. Goth. 170. 
The fate earth or humus fchifti Syf. Nat. 51 1. 
owes its origin to flute , diftolved by the air, 
rain and fnow. 
Ochre is formed of metals difiblved, w r hofe 
faeces prefent the very fame colours, which 
we always find the ore tinged with, when 
expofed to the air. Vitriol in the fame 
man- 
