22 The Principles of Part I. 



to its metallic form By this experiment 

 the oil was got in a feparated ftate from the 

 earthy parts, which after this feparation 

 had loft their tenacity. This gentleman's 

 experiments {how us how ftrongly the oil 

 and earth adhere ; for the oil was fcarcely 

 feparable by fpirit of wine. 



Exp. 7. When a piece of the clay was 

 kept in the kitchen-fire for fome time, it 

 turned red like a live coal, and when taken 

 put, had a high red colour, which feemed 

 owing to the particles of iron that it con- 

 tained. Very few particles indeed were at- 

 tracted by the magnet. But it muft be re- 

 membered, that this quality depends upon 

 the inflammable part of that metal, which 

 is always given it by art, and that I had 

 not added oil in the calcination. Very 

 few ores have this quality naturally. All 

 thefe experiments were made on the fame 

 clay. 



