PHYSICAL AND LITERARY. 25 



E X P E R. XVII. 



A piece of the marie of Experiment 3» 

 weighing 80 graias, was kept in a flrong 

 fire for two hours. Its weight was there' 

 by reduced to 52 grains, apd its colour, 

 from a blueifh white, changed to a reddifli 

 brown. Jts hardnefs was at the ikme 

 time confiderably augmented ; and tho', 

 "when immerfed in its natural ftate into 

 water, it gradually relented and fell dowa 

 into powder ; yet now it neither fufFered 

 any change from that fluid, nor commu- 

 nicated to it any thing perceptible by 

 the fight, tafle, or fmell. Notwithlland- 

 ing this, when it was reduced to pow- 

 der*, it afforded, upon the affufion of wa- 

 ter, as pungent lime-water as any quick- 

 lime could do. 



EXPER. 



* The pulverization of al! burnt marles, that contaia 

 any confiderable proportion of day, is ablolutely necef- 

 l" fary to extraft a liine-\yater from them. Inattention to* 

 fhis circumftance has, 1 believe, produced ibme milhkes. 

 yvhen fhell-marle is burnt, pulverization is leJdom requiv 

 file } becaufe, this fubftance being naiuraUy of a looi^ 



and 



