134 



CHEMICAL COMPOSITION OF KARROO ASH. 



fat, tallow, and beef -suet are also by-products on most farms. 

 As potassium carbonate is, so to speak, the starting-point 

 in the production of all potash compounds, its uses are many, 

 one being the formation of cyanide of potassium, employed 

 largely in gold extraction. 



To the above excellent summary of the conditions under 

 which Karroo ash comes into existence, it is not necessary to 

 add any further explanation. Mr. Croghan, in the course of his 

 paper, presented a series of twenty-five chemical analyses of the 

 sheep or kraal manure, from which the Karroo ash is derived. 

 Of the samples analysed, 14 were produced within the Cape 

 Province, and 11 in the Orange Free State. In each case the 

 manure was allowed to become air-dry before being analysed, 

 and it will serve a most useful purpose to tabulate the following 

 summary of the results so arrived at : — 



Calculated on the perfectly dry material the above averages 

 become : — 



Organic 

 Matter. 



Per 

 cent. 



Ash. 



Per 



cent. 



Phospho- 

 Potash. Lime, rus Pent- Nitro- 



Per 



cent. 



Per 



cent. 



oxide. gen. 



Per Per 

 cent. cent. 



Cape Province 60.33 39-67 4-36 3.89 .86 1.24 



Orange Free State . . . 54.37 45.52 3.93 2.90 .83 1.44 



, Basing the assumption on these figures, the average Karroo 



ash, if perfectly pure, would contain the following percentages: — 



Potash. Lime. Phosphorus 



Pentoxide. 



Cape Province 10.99 9-8i 



Orange Free State . . . . 8.63 6.37 



The better quality of the ash from the Cape Province, as 

 well as its smaller proportion in the unburnt manure, was prob- 

 ably due to the Orange Free State samples having been more 

 largely mixed with sand than those from the Cape. How 

 curiously such admixtures afifect the quality of the manure when 

 burnt we shall see later on. 



2.17 



1.82 



