PHYSICAL AND LITERARY.45 



to be conneded farther than the clay 

 can be properly extended. For this rea- 

 fon it is, that a greater proportion of fand 

 than what is employed in this Experi- 

 ment, gives a compofition, which the ac- 

 tion of fire renders unable to refill wa- 

 ter in the fmallefl degree. Compare Ex- 

 periments 7. and 8. with Experiment 

 18. and ipk . 



EXPER, XXVII. 



Six parts of chalk, two parts of fand, 

 and one part of clay, gave a compofition, 

 which, when calcined and put into wa- 

 ter, immediately fell down into powder. 

 I have feen a lime-ilone confiding of the 

 fame proportion of earths. 



It may be remarked, that tho' the 

 laft compofition, and that of Experi- 

 ment 24. quickly relented in water, after 

 calcination; yet m.any little mafles in 

 both fuffered no change. This was pro • 

 bably owing to fome inequalities in the 

 mixture, by which the particles of clay 



were 



