1 8 ESSAYS AND OBSERVATIONS 



Marie conrifts of two parts, poOefTcd of 

 very op polite quaUtic's. The one, clay, 

 or a mixture of cLiy and fand ; the q- 

 ther, a fubfcance foluble in acids, con- 

 vertible by calcination into quick-lim^, 

 and confeqnently a real calcarious earth, 

 differing in no reipedl from the calcari- 

 ous earth of lime-ftone and the Ihells of 

 animals.* 



From the foregoing experiments it is 

 alfo manifeft, that the nature of clay- 

 marles, llone-marles, and ilate-marles, is 

 altogether tlie fime. For marles of q- 

 qual purity, and confilling of the lame 

 proportions cf conftituent earths, are 

 found under all thefe dlilcrent appearan- 

 ces. Different nam^es have been utfixed 



to 



* The very efllnce of ma^le feeras to coc.CH in this 

 earth ; foi- that nau.e is beftcwed on no lubftocce ti.at 

 does not contain an earth cf this nature. However, ali 

 bodies, into whole couipoliiion cakarioue earth enters, 

 do not fall ur-'^er the c^encnr.ination of marie. To 

 intitle them to this, they oiult fail into powder 

 upon being exjined to the air, Plence, the purity of 

 inari<;5\vill be in proportion to the quantity of calcariou* 

 earth in their con-pofitioa- 



