MINERALOGY. 97 



with any other kind of earth, by which it 

 •might be confidered as a variety of any 

 other. That which is here defcribed, is of 

 a yellow colour, and is fold by druggifts, 

 who do not know where it is found *. 



SECT. XC. 



E. Common Clay, or Brick Clay, Argilla com- 

 munis •, vulgaris Plajlica. 



This kind mav be ,diftino;uiihed from the 

 other clays, by the following qualities. 



1 . In the fire it acquires a red colour, more 

 or lefs deep. 



2. It melts pretty eafily into a greenifh 

 glafs. 



3. It contains a fmall quantity of iron and 

 ef the vitriolic acid, by which the pre- 

 ceding effects are produced. 



It is found, 

 A. Diffusible in water. 

 j. Pure. 

 A. Red clay, from Kinnekulle, in 

 the province of Weftergottland. 



b. Flefh coloured, or pale red, is 

 found on the plains between Wef- 

 teras and Sala, in the province of 

 Weftmanland. 



c. Grey, in the corn-fields in the pro- 

 vince of Upland. 



• I have got of this kind of tripoli from Scotland, which 

 has been lately difcovered there. But the rotten-ftorte, fo 

 called, is another fort found in England, viz. in Derbyfhire. 

 It is in common ufe here in England among workmen for 

 all forts of finer grinding and polifhing, and is alfo fome- 

 ■xima ufed by lapidaries for cutting of ftones, &c. D. C. 



H «*• d. Bins 



