NOTES ON THE CHEMICAL COMPOSITION OF 



KARROO ASH. 



By Charles Frederick Juritz, M.A., D.Sc, F.I.C. 



At the joint meeting of the British and South African 

 Associations for the Advancement of Science, in 1905, a paper 

 by Mr. E. H. Croghan, F.C.S., was read, entitled " A fuel of the 

 Midland Districts of South Africa."' The paper was subse- 

 quently printed in full in the proceedings of the meeting pub- 

 lished by the South African Association,* but for the present 

 purpose it will suffice to quote the summary thereof printed in 

 the British Association Report.! This summary is as follows : 



The region known as the Midland Districts is dry and 

 treeless, with a scarcity of rainfall. The better part of 

 this region is suitable for sheep-farming, being sparsely 

 covered with bushes, the foliage of which constitutes the 

 chief food of sheep and cattle. These bushes are very 

 hardy, and have an enormous root system, penetrating to a 

 great depth. They are of great nutritive value, as they 

 contain a comparatively large (|uantity of digestible carbo- 

 hydrates, principally starch. These carbohydrates are 

 associated in the plant system with potash compounds ; 

 therefore we also find a large quantity of potash in sheep 

 excreta. This manure accumulates in considerable quantity 

 in the kraals (a sort of paddock near the homestead). The 

 farmer has no use for this manure as such, because he has 

 no water for irrigation, and gets a very indifferent supply 

 from his wells. In some parts of the sheep districts it is 

 a well-known fact that the drought is often so severe that 

 the lambs are killed to save the ewes. The farmer there- 

 fore uses the dung only as fuel. He has it dug out and 

 cut into bricks, somewhat resembling those made of spent 

 tan, which in some continental countries are similarly used 

 as fuel. The ashes are thrown aside, and frequently 

 accumulate as small mounds near the homestead. 



These ash-heaps, as well as the manure itself, are of 

 great economic value, more particularly for heavy, clayey 

 soils. The Cape farmer obtains a fair su])ply of guano 

 from the Guano Islands along the coast, and if he were to 

 supplement this with ashes of sheep dung, thus supplying 

 the necessary potash (guano being principally of a nitro- 

 genous and phosphatic nature), he would secure an excellent 

 manure for raising all kinds of grain and root crops, espe- 

 cially potatoes. For industrial or domestic purposes these 

 ashes may be used for the production of potassium car- 

 bonate, which can be employed in making soft-soap, since 



'^Addresses and papers read at the joint meeting of the Brit, and S.A. 

 Assns. for Adv. of Se. (1905), 1, 237-246. 



"fRept. Brit. Assn. for Adv. of Se., South Africa (190.S). 2>7i' 374- 



