[ ^55 ] ' 



~ 4 



and is the true bafis of their amelliorating powers ; if the water 

 that paffes through a putrefying dunghill be examined it will 

 be found of a brown colour, and if fubjeded to evaporation 

 the principal part of the refiduum will be found to confift of 

 coal *. All foils fteeped in water communicate the fame colour 

 to it in proportion to their fertility, and this water being eva- 

 porated leaves alfo a coal, as Mr. HafTenfraz and Fourcroy atteft -j-. 

 They alfo obferved that fhavings of wood being left in a moift 

 place for nine or ten months began to receive the fermentative 

 motion, and being then fpread on land putrefied after fome 

 time and proved an excellent manure J. Coal, however, cannot 

 produce its beneficial efFeds but in as much as it is foluble in 

 water ; the means of rendering it foluble are not as yet well 

 afcertained ; neverthelefs it is even now ufed as a maniu-e, and 

 with good eifed §. In truth the fertilizing power of putrid, 

 animal and vegetable fubftances were fully known even in the 

 remoteft ages, but moft fpeculatifts have hitherto attributed 

 them to the oleaginous, mucilaginous, or faline particles then 

 developed, forgetting that land is fertilized by paring and burnings 

 though the oleaginous and mucilaginous particles are thereby 

 confumed or reduced to a coal, and that the quantity of mucilage 

 oil or fait in fertile land is fo fmall that it could not contribute 

 the loooth part of the weight of any vegetable, whereas coal 

 is fupplied not only by the land but alfo by the fixed air com- 

 bined with the earths, and alfo by that which is conftantly fet 

 loofe by various proceffes, and foon precipitates by the fuperiority 

 of its fpecific gravity, and is then condenfed in, or mechanically 



U 2 abforbed 



* 74 An. Chy. 56. f Ibid. % Ibid. § Young's Annals. 



