BOOK XVII. IV. 45-48 



a narrower mouth but with the shaft expanding in the 

 interior, as is the practice in mines. This chalk is 

 chiefly used in Britain. Its efFect lasts for 80 years, 

 and there is no case of anybody having scattcred it on 

 the same land twice in his lifetime. A third kind of 

 white marl is called g/;*o;nrtrga ; this is fullers' chalk 

 intermixed with a greasy carth, and it is a more etfec- 

 tive dressing for pasture than for corn, so that, when 

 a crop of corn has been carried, before the next 

 sowing a very abundant crop of hay can be cut, 

 although while growing corn the land does not produce 

 any other plant. Its effect lasts 30 years ; but if it 

 is scattered too thickly it chokes the soil just as 

 Segni plaster does. For dove-coloured marl the 

 GaUic provinccs have a name in their own language, 

 eglecopala ; it is taken up in blocks hke stone, and is 

 split by the action of sun and frost so as to form ex- 

 tremely thin plates. This kind of marl is equally 

 beneficial for corn and grass. Farmers use sandy 

 marl if no other is available ; but they use it on damp 

 soils even if another sort is available. The Ubii are 

 the onlv race known to us who while cultivating 

 extrcmely fertile land enrich it by digging up any 

 sort of earth below three fcet and tlirowing it on 

 the land in a layer a foot thick ; but the benefit of 

 this top-dressing does not last longer than ten years. 

 The Aedui and the Pictones have made their arable 

 land extremcly fertile by means of chalk, which is 

 indeed also found most aseful for olives and vines. 

 But all niarl shoukl be thrown on the hind after it has 

 been ploughed, in order that its medicinal properties 

 niav bf absorbed at once ; and it requires a moderate 

 amount of dung, as at first it is too rough and is 

 not ditfused into vegetation ; otherwise whatever 



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