154 Report S.A.A. Advancement of Science. 



4 said to consist mainly of wolves' dung (Wonderfontein). 



5 contained many bones (Wonderfontein). 



6 was a recent deposit, bats' dung and silt (Wonderfontein). 



7 a recent deposit from Elandsfontein caves, near Pretoria. 



In certain districts it is the custom to employ dried sheep's dung 

 as fuel on the farms. Sheep's kraal manure, used as fuel under the 

 name of " Mest," was found by Lewis in 1899 to contain (average 

 of 1 1 samples) : — 



While E. H. Croghan, in a paper read last year before the 

 British Association at Johannesburg, found 25 samples from Cape 

 Colony and the Orange River Colony contained : — 



Nitrogen 0.55 to 1.68, mean 1.22 per cent. 



Potash 1.23 to 5.86 ,, 3.85 ,, ,, 



Phosphoric acid 0.38 to 1.28 ,, 0.78 ,, ,, 



the ash left when " mest " is burnt is free from nitrogen, but 

 much richer in potash and phosphoric acid. 



Lewis found, as a mean of 3 samples :— 



Potash 7.60 per cent. 



Phosphoric acid 2.59 ,, ,, 



While Croghan, in 25 samples, found quantities ranging from : — 



Potash 3.74 to 18.57 per cent 



Phosphoric acid 1.20 to 3.50 ,, ,, 



In certain parts of the Transvaal are old cattle kraals, used by 

 the natives before the incursions of white men. The deposits over- 

 lying these kraals are almost devoid of nitrogen, but still retain 

 considerable quantities of potash and phosphoric acid. A specimen 

 of such deposit, from near Rustenburg, from a kraal said to have 

 been used about a hundred years ago, was found to contain : — 



Potash 1.52 per cent. 



Phosphoric acid 2.00 ,, ,, 



This deposit has been largely used by the local farmers with 

 successful results during the last 7 or 8 years, when kraal manure has 

 been scarce. 



Another remarkable source of phosphoric acid has come under my 

 notice — the ash of certain Transvaal coals. In a specimen of coal 

 ash from one of the Witbank Collieries I found 5.5 per cent, of 

 phosphorus pentoxide. 



