192 



CHEMICAL MANURES. 



Moreover, it contains much sand. None the less, it is in much re- 

 quest for the manufacture of superphosphate, because it can be 

 treated without any previous preparation. Spent char contains 25 

 to 75 per cent of phosphate of hme, 1-5 to 15 per cent of carbonate 

 of hme, and up to 1 per cent of sulphate of lime. Spent char dust 

 contains much less of these substances. As the granular char re- 

 moves nitrogenous impurities from the saccharine juices, it also 

 contains up to 1 per cent of nitrogen. Some analyses of animal 

 charcoal, both before and after its use in the clarification of syrups, 

 are given in Table LI. 



TABLE LI. 



-ANALYSES OF NEW AND USED AND SPENT BONE 

 CHAR. (PIERRE.) 



Bone Ash. ^ — The immense prairies of South America support 

 numerous herds of cattle ; 1000 head of cattle per inhabitant can 

 be counted in many of these countries. The animals are 

 slaughtered for their horns, their skins, and their fat. The flesh is 

 rarely utilized for human food. It is left to rot, or even as food 

 for wild animals. The bones are dried and used as domestic fuel and 

 in the tallow smelteries, sugar factories, etc., for other fuel is scarce 

 in these districts. It was in that way that from 100 to 200 years 

 back hillocks of bone ash accumulated near dwellings for which, 

 till a short time ago, no use was found even as a manure. But owing 



^ Bone ash is very hard and difficult to grind, besides it is always wet by 

 absorption of moisture apparently from the air, and is best dried on the engine 

 ste.im boilers, over which for the time being it acts as a non-conducting com- 

 position. Bone ash yields an excellent superphosphate with about 40 per cent 

 of soluble phosphate and 1 per cent of insoluble. It is sometimes a little 

 bit difficalt to dry, but it takes kindly to the kiln. The manure manufacturer 

 keenly feels the want of supplies of this most valuable product. A cheap 

 machine that would burn spent char to bone ash cheaply and rapidly would 

 supply a great want and enable spent char to till the place of bone ash, which it 

 cannot now do, as its colour debars it. Bone ash superphosphates, it is needless 

 to say, never retrogrades. — Tr. 



