100 



Report S.A.A. Advancement of Science. 



In a paper recently read by nie before the Cape Chemical Society,* 

 reference was made to the Orange Ri\er clay collected in the Prieska 

 division ; samples of soil from farms situated along the river banks 

 lower down were also taken ; these, in each case, represented the 

 surface-soil to a depth of 12 ins., and the subsoil from 12 to 24 ins.^ 

 and fiom the latter depth to 3 ft. Of all these, mechanical analyses 

 were made, with the results summarised below : — 



No. 1 was a sample of the silt carried down by the Orange River 

 while in flood, and fleposited by the ri\'er when receding within normal 

 limits after overflowing its banks. The sample was collected at the 

 western boundary of the Government farm Zeekoe Baard, near the 

 Buchuberg irrigation works. Large tracts of countrj' in this vicinity 

 are covered by the blown sands of the Kalahari, and along the river 

 banks a continual intermingling of the alternating blown sands and 

 river silts is in progress. Of these mixtures Nos. 2, 3 and 4 are 

 samples ; they were taken from the centres of each of the large tracts 

 of irrigable land — No. 2 froin the farm Stofkraal, ilj miles down the 

 ri\er from the irrigation works; Nos. 3 and 4 from the farm Keuken 

 Draai, at distances respectively 14 and 16 miles from the works. 



Rich though it may be chemically, the Orange River deposit 

 contains too much clay, and is therefore too dense and heav}- to enable 

 it to be advantageousl}' used in its original condition : but when 

 deposited on the surface of a sandier soil, with which it may be 

 manipulated, it would add considerably to the agricultural \alue of 

 the latter. If it could be directed on to a ver}' sandy soil, containing, 

 say, 90 per cent, of sand, a single flooding of the lands would^assum- 



Vide Cope of Good Hope Ac/ricvltural Joitrnal, Sept., 1907, pp. 295-99. 



