VOLUME AND PERIODICAL EISING OF THE NILE. 



73 



millions of people dwell in the Nile basin, wliicli might yield corn sufficient for a 

 vastly larger population. 



The brown or blackish mud of the Nile is the only manure required for the 

 crops. In the sun it becomes solid and may be cut into bricks or vessels ; under the 

 foot it is hard as stone, and in shrinking develops deep fissures in the ground. 

 The old sandy or calcareous deposits, mingled at the foot of the hills with the rolled 

 shingle washed down by floods anterior to the present geological epoch, are covered 

 with a layer from 35 to 40 feet thick, forming an extremely rich arable soil which, 

 if removed elsewhere, might suffice to fertilise a region a hundred times more 

 extensive. 



In its chemical composition this Nile mud, from which Egypt has been created, 

 differs from that of all European rivers. Its analysis yields the most varied results 

 according to its age, locality, and distance from the river. But it always contains 

 a considerable proportion of carbonates of lime and magnesia, of oxide of iron and 

 carbon, derived from decomposed organic substances. Palatable as it is, the Nile 

 water nevertheless contains the refuse of all the provinces in its vast basin — the 

 slime of the Atbara, animal remains from the Bahr-el-Azraq lagoons, sedge and 

 other vegetable débris from the Kir and Gazelle rivers. Between the sands, argil- 

 laceous clays, and rugged crags of both deserts there thus intervenes a narrow belt 

 of verdure created by the miscellaneous sedimentary matter in the course of ages 

 washed down from half the continent.* 



* Analysis of the Nile mud in Egj'pt, by Regnault, " Description of Egypt," vol. xx. 



Water 

 Carbon 

 Oxides 

 Silica 



1 1 per cent. 



9 „ „ 

 6 „ „ 



Carbonate of Magnesia 

 Carbonate of Lime . 

 Alumina . 



4 per cent. 

 18 „ „ 

 48 „ ,, 



