MARL. 85 



as it will tend to bind the land, and cause it to retain 

 every thing that falls upon it. On stiff soils a thin 

 coat should be spread, sufficient to render it more po- 

 rous, by which it may receive and retain whatever 

 falls upon it. 



" To find the composition of marl, 55 says the Do- 

 mestic Encyclopedia, " pour a few ounces of diluted 

 muriatic acid into a Florence flask ; place them in a 

 scale, and let them be balanced ; then reduce a few oun- 

 ces of dry marl into powder ; and let this powder be 

 carefully and gradually thrown into the flask, until af- 

 ter repeated additions, no farther effervescence is per- 

 ceived. Let the remainder of the powdered marl be 

 weighed ; by which, the quantity projected will be 

 known. Let the balance be then restored. The dif- 

 ference of weight between the quantity projected and 

 that requisite to restore the balance, will shew the 

 weight of air lost during effervescence. [That air 

 proceeds from the calcareous earth alone, which con- 

 tains 44 per cent, of this carbonic acid air. Suppose 

 500 grains of marl lose 44 grains by the escape of air, 

 then that marl contained 100 grains, or one-fifth of its 

 whole weight of limestone. T. C.] If the loss 

 amount to twenty or twenty-five per cent, of the quan- 

 tity of marl projected, the marl assayed is calcareous 

 marl, or marl rich in calcareous earth. Clayey marls, 

 or those in which the argillaceous ingredient prevails, 

 lose only 8 or 10 per cent, of their weight by this 



treatment, and sandy marls about the same proportion. 

 8 



