2SO MATERIALS OF INDIRECT VALUE [chap. 



For example, Pliny writes : — " There is another way 

 of nourishing earth by earth, which has been found out 

 in Britain and Gaul. It is thought that there is a 

 greater degree of fruitfulness in this kind than in any 

 other. It is a certain richness of earth, like the kernels 

 in animal bodies, that are increased by fatness. " The 

 principal of those, reckoned the fat kinds, is the 

 white ; of this there are many. One very acrid, that 

 has already been mentioned. Another kind of the 

 white is like a soft clay. It is found at a great depth ; 

 the pits very frequently dug an hundred feet down, 

 narrow at the mouth ; but the vein, as in metals, 

 widening within. This is chiefly used in Britain. It 

 remains eighty years ; nor is there an instance of any 

 man laying it twice on the same field. "The Hedui 

 and Pictones manure their fields with lime, which is 

 likewise found very good for olives and vines. All 

 marl ought to be laid upon ploughed land, that 

 its virtue may be the easier sucked in by the soil. A 

 little dung should be laid on with it, particularly with 

 that kind that at first is too hard, and does not dissolve 

 well enough to nourish plants. Besides, of whatever 

 kind it is, it hurts the soil, by its being new, and does 

 not render it fertile till after the first year." 



The regular use of some form of lime or chalk was 

 part of the accepted routine of farming as early as we 

 possess any records of British agriculture, and among 

 the manures it figures in all books of the sixteenth and 

 seventeenth centuries. In fact "the black and the 

 white," dung and lime, were the only manures employed 

 by the great mass of farmers until well into the 

 nineteenth century. 



Lime itself, or quicklime, is obtained by the " burning " 

 of any form of calcium carbonate, which occurs as 

 limestone [either pure in the Mountain Limestone of 



