PHYSICAL AND LITERAiRY. <^ 



SECT. III. 

 E X P E R. IV. 



THE fubflance which remained in 

 the filter poflelTed, almoft in every re- 

 fpedl, the properties of clay. In dry- 

 ing it concreted into a mals of confide- 

 rable hardnefs ; made no efFervefcence 

 with any of the acids ; fell down and dif* 

 fufed readily in water j and was, by the 

 adlion of fire, converted into a reddifh- 

 coloured brick. vTwenty grains of fuch 

 a fubilanceextradledfrom the fame marie 

 gave, by elutriation *, 5 grains of fand. 

 Hence the nature of the unfoluble part 

 of this marie i^ abundantly evident. 



It muft be remarked, however, that 



neither the quantity nor compolirion of 



this unfoluble partis, in any two marles, 



precifely the fame. Clav, or clay and 



Vol. III. B ' fand, 



• This term is applied to the feparation of clay frona 

 fand by means of water, 



