BOOK XVII. IV. 42-45 



name of leucargillum to a white clay that they use on 

 the land at Megara, biit only where the soil is damp 

 and chilly. The other substance brings wealth to 

 the provinces of Gaul and Britain, and may suitably 

 receive a careful description. 



There had previously been two kinds of marl, but 

 recentlv with the progress of discoveries a larger 

 number have begun to be worked : there is white marl, 

 red marl, dove-coloured marl, argillaceous marl, tufa 

 marl and sand marl. It has a two-fold consistency, 

 rough or greasy, each of which can be detected by its 

 feel in the hand. Its use is correspondingly double, 

 to feed cereals only or to feed pasture-land as well. 

 Tufa marl nourishes grain, and white marl, if it is found 

 where springs rise, has unlimited fertiHzing properties, 

 but it is rough to handle, and if it is scattered in ex- 

 cessive quantities it scorches up the soil. The next 

 kind is the red marl, which is known as acaunumarga,'* 

 consistincr of stone minffled with a thin, sandv earth. 

 The stone is crushed on the land itself, and in the 

 earHest years of its employment the fragments make 

 the comstalks difficult to cut ; however, as it is ex- 

 tremely Hght it can be carried for only half of the 

 cost charged for the other varieties. It is scattered 

 on the land thinly ; it is thought to contain a mixture 

 of salt. With both of these kinds a single scatter- 

 ing serves for fifty years to fertiHze either crops or 

 pasture. 



Of the marls that are greasy to the touch the chief 

 one is the white. It has several varieties, the most 

 pungent being the one mentioned above. Another §§ 43-44. 

 variety of white niarl is the chalk used for cleaning 

 silver; this is obtained from a considerable depth in 

 the ground, usually from pits made 100 feet deep, with 



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