[ >34 ] 



If dry It adheres more or lefs to the tongue, if thrown into 

 water it gradually difFufes itfelf through it, and flowly feparates 

 from it. It does not ufually efFervefce with acids, unlefs a ftrong 

 heat be applied, or that it contains a few calcareous particles or 

 magnefia. If heated, it hardens and burns to a brick. 



It confifts of argill and fine fand, ufually of the filiceous kind, 

 in various proportions, and more or lefs ferruginous. The argill 

 forms generally from 20 to 75 per cwt, of the whole mafs, the 

 fand and calx of iron the remainder. Thefe are perfe<flly feparable 

 by boiling in ftrong vitriolic acid. 



Chaik, if not very impure, is of a white colour, moderate 

 confiflence, and dufty furface, ftains the fingers, adheres flightly 

 to the tongue, does not harden when heated, but, on the con- 

 trary, in a ftrong heat burns to lime, and lofes about -*- of 

 Rs weight ; it efFervefces with acids and diflblves almoft entirely 

 therein. I ftiall alfo add that this folution is not difturbed by 

 cauftic volatife alkali, as this circumftance diftinguiflies it from 

 magnefia — it promotes putrefadion. 



Sand. By this is meant fmall loofe grains of great hardnefs 

 not cohering with water, nor foftened by it ; it is generally of 

 the filiceous kind, and therefore infoluble in acids. 



Gravel differs from fand chiefly in fize^ however, ftones 

 of a calcareous nature, when fmall and rounded, are often 

 comprehended under that denomination. 



Loam 



