Chap. VIII. O F M A N U R E S. 31 



inarkably aftringent. It agrees with marie, in crumbling in water; 

 but it differs remarkably from it, in raifing no effervescence with 

 acids, nor in the leafl deltroying their acidity. It turns the fyrup of 

 violets red ; which fliews that it contains an acid : whereas marie, 

 like all abforbent earth, gives it a green colour. 



It appears from experim.ents made by the doftor, that this fub- 

 Aance conlills of an earthy body like clay, about one eighteenth part 

 of fait of fteel, and a fmall proportion of the vitriolic acid : and he 

 concludes, that mark is the proper cure where this noxious earth has 

 been inadvertently ufed, becaufe it corrects the acid, and decompofes 

 the fait. 



III. Of Loam. 



T 0AM, being free from the too great ffiffnefs of clav, and the too 

 ■^-' little cohefion of fand, in order to its due culture, feems only to 

 ffand in need of being kept in good tilth, and fupplied at proper fea- 

 fons with fuch fubftances as- the experience of ages has fhewn to con- 

 tain in them matter fit for the nourUhment of plants, or at leafl: to 

 be indued with the power of rendering the earth fruitful. Such 

 fubftances we fliall therefore call general manures. Of thefe, dung§ 

 of all kinds, putrid vegetable and animal fubftances, alhes of vege- 

 tables, and even of fea-coal and peat, foot, and lime, are the chief. 



Dungs, as Mr. Miller obferves, are defigned to repair the decays 

 of exhaufted worn-out lands, and to cure the defefts of land, which 

 are as various in their qualities as the dungs are, that are ufed to me- 

 liorate and reftore them. Some lands abound too much in coldnefs, 

 moifture, and heavinefs ; others again are too light and dry; and fo, 

 to anfwer this, fome dungs are hot and light, as that of ftieep, horfes, 

 pigeons, &c. others again are fat and cooling, as that of oxen, cows, 

 hogs, &c. And as the remedies that are to be ufed, muft be contrary 

 to the diftempers they are to cure ; fo the dung of oxen, cows, and 

 hogs, muft be given to lean, dry, light earths, to make them fatter 

 and clofer ; and hot and dry dungs to meliorate cold, moift, and 

 heavy lands. 



There are, continues he, two peculiar properties" in dung : the 

 one is to produce a certain fenfible heat, capable of producing fome 

 confiderable effed:, which properties are feldom found but in the 

 dung of horfes and mules, while it is newly made, and a little moift : 

 the other property of dung is, to fatten the earth, and render it more 

 irui.ful. 



The 



