unite with the air unlefs it is previoufly moiftened. loo parts 

 quick-hme abforb about 28 of water. It is foluble in about 

 700 parts of this fluid. To regain its full portion of air from 

 the atmofphere it requires a year or more, if not purpofely 

 fpread out ; it refifts putrefadion ; but with the afliftance of 

 moifture it refolves organic fubftances into a mucus. 



Marle is of three forts, calcareous, argillaceous, and filiceous 

 or fandy. All are mixtures of mild calx (/. e. chalk) with 

 clay, in fuch a manner as to fall to pieces by expofure to the 

 atmofphere, more or lefs readily. 



Calcareous Marle is that which is moft commonly under- 

 ftood by the term Marie without addition. It is generally of 

 a yellowifh white, or yellowifh grey colour, rarely brown or 

 lead coloured. It is fcldom found on. the furface of land, but ■ 

 commonly a few feet under it, and on the fides of hills, or 

 rivers that flow through calcareous countries, or under turf in 

 boggs — frequently of a loofe texture, fometimes moderately co- 

 herent, rarely of a ftoney hardnefs, and hence caAeA Jlone marle -f' 

 fometimes of a compad, fometimes of a lamellar texture, often 

 fo thin as to be called paper-marle ; it often abounds with 

 fliells, and then is called Jhell-marle, which is looked upon as 

 the beft fort — when in pow'der it feels dry between the fingers, — 

 put in water it quickly falls to pieces or powder, and does not- 

 form a vifcid mafs — it chips and moulders by expofure "to the" 

 air and moifture, fooner or later, according to its hardnefs and 

 the proportion of its iiigredienfs ; if" heated it will not forma- 

 brick, but rather lime ; it effferv^cies with all' acids ; it confifts 



of 



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