138 CHEMICAL COMPOSITION OF KARROO ASH. 



Lewis, was proceeded with on the following lines : The samples 

 were all exposed to the air until air-dry, and the percentages of 

 moisture in the air-dry samples were then determined. Portions 

 were then burnt to ash, and the ratio of asli to the raw manure 

 determined, after which the chemical analysis of the ash itself 

 was proceeded wnth. 



Mention has already been made of the fact that the manure 

 heaps are often allowed to accumulate for many years. In the 

 Cradock Division one such heap was sampled, hrst at the top 

 (No. 9), then at a depth of four feet (No. 10). and finally 

 six feet deep (No. 11). Table I shows the percentage results 

 of the analyses of the chemically pure ash of each of these. The 

 other samples collected were: Nos. 12, Beaufort West; 13, 

 Colesberg; 14, Steynsburg ; 15, Aberdeen; 16, Graafif-Reinet ; 

 17, Middelburg ; 18, Laingsburg ; 19, Swellendam ; 20, Middel- 

 burg; 21, Klipplaat, Jansenville; and 22, V'ictoria West. It is 

 worth drawing special attention to the fact that the phosphorus 

 pentoxide in all the above samples proved to be citrate-soluble — 

 i.e.. it was in a form readily available as plant-food. 



In Table I, Nos. 20 to 22, like the other analyses of this set 

 of samples, represent the chemically pure ash, not the ash as 

 obtained in the first instance on the farms, that ash having under- 

 gone a further combustion in the laboratory in order to yield 

 tht results above tabulated. For the purpose of comparing the 

 farm-ash and the laboratory-ash, the following table furnishes 

 the full results of analyses of Nos. 20 to 22 after their first 

 burning — i.e., just as they arrived in the laboratory: — 



If the manures represented by the above table of analyses 

 had been burnt on the farms, the ash obtained would have been 

 more impure, for it would in each case have contained a great 

 deal of charred organic matter, which, while adding to the bulk 

 of the ash, adds nothing to its fertilising value. 



During the year 1900 two further specimens (Nos. 23 and 

 24) were examined, at the instance of the Fruit and Vine 

 Growers' Association. Stellenbosch. Only one of these. No. 

 23, was a farm-burnt Karroo ash, obtained from the farm Zout 

 Kloof, Laingsburg, and was not expected to be a fair sample, 

 as only a small quantity of manure had been burnt, and so it 

 would necessarily be somewhat mixed with ash derived from 

 the wood used for starting the combustion. This would not 

 be the case when a kiln of the manure is allowed to continue 

 burning day and night without being supplemented by wood. 

 No. 24 arrived in the laboratory in the unburnt condition, and 

 was there reduced to pure ash, the raw manure containing 15.37 

 per cent, of water, and yielding 39.99 per cent, of ash. Of 



