PHYSICAL AND LITERARY. 197 



colledted with the greateft care, and dryed, 

 weighed, as nearly as I could guefs, one third 

 of a grain. The water tafted ftrongly of the 

 lime, had all the qualities of lime-water, and 

 yielded twelve grains of precipitate, upon the 

 addition of fait of tartar. In repeating this 

 experiment, the quantity of fediment was 

 fometimes lefs than the above, and fometime§ 

 amounted to half a grain. It coniifted part- 

 ly of an earth which effervefced violently 

 with aqua fords, and partly of an ochry pow- 

 der, which would not diiTolve in that acid* 

 The ochry powder, as it ufually appears in 

 chalk to the eye, in the form of veins running 

 thro' its fubftance, muft be conlidered only 

 as an accidental or foreign admixture ; and, 

 with refpedt to the minute portion of alkaline 

 earth which compofed the remainder ^f the 

 fediment, it cannot be fuppofed to have beei> 

 originally different from the reft, and incapa-i 

 ble, from its nature, of being converted, .into 

 quick-lime, or of being difTolved in vvater j 

 it feems rather to have confifted of a fmall 

 part of the chalk in its mild ftate, or fatu- 

 rated with air, which had either remained, for 

 want of a fufficient fire to drive it out entirely. 

 Of had been furnillied by the diftilled water. 



I 



