Proceedings of the Farmers' Club. G87 



Phosphate Org^v^^^ic Manures. 



Altliongli poudrette, especially the double refined, contains a fair 

 amount of phosphoric acid, and of course such a proportion of soluble 

 l^otash as may have existed in the organic matter from which the 

 material is produced, it is properly speaking, an annnoniated manure, 

 because of the excess of the ammonia it contains. On the other hand 

 the manures made from bones, which constitute one form of organic 

 matter, owe their chief value to the presence of phosphoric acid, the 

 ammonia, except in the case of raw or unboiled bones, existing in 

 only a trifling proportion. Some twenty yeare ago it was the prac- 

 tice to convert tlie bones into superphosphate by treatment with dilute 

 sulphuric acid, but of late this appears to have become obsolete, partly 

 because the use of mineral phosphates has enabled a' good superphos- 

 13liate to be made at a much lower price than would be possible vv'ith 

 bones alone, and partly because a large class of farmers prefer, for cer- 

 tain crops, the pure bone in the form of dust or flour to any super- 

 phosphate. For this reason the bones, which are mostly obtained 

 from the western cities where large numbers of cattle are slaugh- 

 tered, are simply ground to diflerent grades of flneness in strong 

 crushing mills. These mills are composed of several pairs of heavy 

 cast iron rollers, arranged one over another. The bones pass between 

 the ui3per pair of rollers, and are broken into fragments. These fall 

 between the second pair and are crushed still finer, and passing thence 

 to a still lower pair are reduced and comminuted until capable of 

 being sifted through the sizing sieves. The product is made of seve- 

 ral different degrees of fineness to suit purchasers ; thus what is 

 termed coarse bone dust is composed of bone ground smaller than 

 one-third of an inch and mixed with an equal cpiantity of the fine 

 bone dust. This latter is made fine enough to pass through sieves 

 with meshes of one-eighth of an inch, while the bone flour, as its 

 name indicates, is made to approach the condition of ordinary flour. 

 The demand for these bone fertilizers is very great, and the supply 

 of bones obtainable quite inadequate to meet it. In addition to those 

 artificial manures, which may be characterized from their greater 

 superabundance of ammonia or phosphoric acid, as the ease may be, 

 there are others in which it is sought to combine both tliese constitu- 

 ents in a more than ordinary degree ; such a manure has been made 

 at these works from some 1,500 tons of mingled bones, pigs' hoofs and 

 hair brought recently from the west, and showing, by analysis, about 

 seventeen per cent of ammonia, in addition to tlie phosphoric acid 



