REPOBT OF CHEMICAL LABOEATOKY 



209 



During the period of flooil of the Blue Nile, the pent-up water of the White, which has 

 a very slight slope (only 1 in 100,000 in flood) forms an immense lake or storage reservoir. 

 The effect of the slowing up of the current is apparently seen in the proportion of 

 suspended matter in September and October, when the figures drop to 23-5 and 32-0 

 respectively. The grosser particles have settled, and there is present chiefly the finer 

 clayey matter. 



The White Nile was thus never found free from an appreciable amount of suspended 

 matter. The Blue Nile, on the contrary, although carrying in flood an enormous amount of 

 mud, later, from January till June, becomes almost clear. The contrast between the two 

 rivers in this respect is best shown by the following diagram, in which is charted, as well, 

 the flood of the Blue Nile from readings of the river levels taken daily by the Department of 

 Works. The figures represent these levels and not the actual volumes of water discharged, 

 but will sufliee for the present comparison. 



Chart Shewing Rel.'^.tion of Flood to the Extent of Suspended Matter 

 Carried by Blue and White Nile Rivers near Khartoum 



Suspended 

 Matter 



Parts 



Million 



1904 

 Nov. 



1905 

 Jan. 



Feb. Mar. .^pril May June July .\ug. Sept. Oct. 



Nov. 



1000 

 900 

 800 

 700 

 600 

 500 

 400 

 300 

 200 

 100 

 



Blie Nile 



Fig. 



White Nile 



KiG. m. 



