[ 139 1 



of from 33 to 8o per cent, of mild calx, and from 66 to 20 per 

 cent, of clay. 



To find its compofition, pour a few ounces of weak, but 

 pure fpirit of nitre or common fait into a florence flafk ; place 

 them in a fcale and let them be balanced; then reduce a few 

 ounces of dry marie into powder, and let this powder be care- 

 fully and gradually thrown into the flaik, until after repeated 

 agitation no effervefcence is any longer perceived; let the 

 remainder of the powdered marie be then weighed, by which 

 the quantity projcded will be known; let the balance be then 

 reftored; the difference of weight between the quantity pro- 

 jeded and that requifite to reflore the balance will difcover 

 the weight of air loft during the effervefcence ; if the lofs 

 amounts to 13 per cwt. of the quantity of marie projeded, or 

 from 1 3 to 32 per cwt. the marie effayed is calcareous marie. 

 This experiment is decifive when we are affured by the external 

 charaders abovementioned that the fubflance employed is marlc 

 of any kind ; otherwife fome forts of the fparry iron ore may 

 be miflaken for marie. The experiments to difcover the argil- 

 laceous ingredient, being too difficult for farmers, I omit. The 

 refidue left, after folution, being well wafhed, will when duly 

 heated, generally harden into a brick. 



Argillaceous Marle contains from 68 to 80 per cwt. of 



clay, and confequently from 32 to 20 per cwt. of aerated calx ■ 



its colour is grey, or brown, or reddifh brown, or yellowifh or 

 bluifh grey— it feels more unduous than the former, and adheres 

 to the tongue— its hardnefs generally much greater— in water 



S 2 it 



