20 MANURES. 5. 



chalk ; its colour being fomewhat darker, and 

 its contexture fomewhat fofter, and more brittle, 

 than the common writing-chalks of Surrey and 

 Kent. 



In the open air, it hreaks readily, and in- 

 corporates freely with the foil. 



In water, it falls in a manner inltanta- 

 neouily * ; but dijfolves not, in any proportion, 

 in this element -f. 



In the fire, it lofes more than one-third of 

 its weight J, and burns to lime^. 



* A piece of this zw^r/ plunged into water fell wida 

 a fmart crackling noife in a few feconds : but a fmall 

 piece of chalk contained in it, received no change frora 

 the water. Hence we have a fimple differential tcjl of thcfe 

 'two foflils. 



■j- One hundred grains pulverized, dried, weighed, 



placed in a filter, flooded repeatedly with cold and warm 

 water, dried, weighed; — received not the fmalleft per- 

 ceptible diminution of weight. 



j A piece, weighing fifty grains, retained in a ftrong 

 fire three hours, loft eighteen grains and a half; weigh- 

 ing, when cool, thirty-one giainj and a half. 



§ The pit from whence the fpeclmen made ufe of 

 ia this analyiis was taken, being worked as a lime-quarry, 

 1 had repeated opportunities of obferving the effect 

 of the lime, both as a manure and a'; a builJing-matcrial. 

 Its Itrength and operation, in both cafes, are, as far as 

 common obfervation can judge, limilar to thofe of the 

 chalk-limes of Surrey and Kcnu 



In 



