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the manufacture of coke. Dried blood for fertilizing pur- 

 poses is chiefly obtained from the large slaughtering establish- 

 ments. Red blood contains from 13 to 14 per cent of nitrogen 

 and is an excellent fertilizer since it decays very rapidly 

 in the soil and is quickly available. 



Fish Scra2_. The waste parts, as heads, skin and bones. 

 It contains from 7 to 8 per cent of nitrogen and from 6 

 to 8 per cent of phosphoric acid. It ranks with the high 

 grade fertilisers. 



Wool an d hair wste . These materials are dissolved 

 with acid in such a manner as to render them available and 

 are quite rich in nitrogen. 



Phoaphate FBrti li zere. 



Bone phosphate in the form of raw bone contains about 

 22 per cent phosphoric acid and 4 per cent of nitrogen. 

 It is a good source of phosphoric acid since it is in its 

 original state and has not lost any of its original con- 

 stituents through burning. Bone-black or animal-charcoal 

 contains from 32 to 36 per cent of phosphoric acid, while 

 bone ask contains from 27 to 37 per dent of phosphoric acid. 



South Carolina Phosphate. This rock contains 26 to 

 28 per cent of phosphoric acid. It sometimes contains small 

 peroeatagea of compounds of iron and aluminum which interfere 

 with the manufacture of the product and are undesirable. 



Phosphate Slag. This is a by-product in the manufac- 

 ture of steel from pig-iron rich in phosph«rus. The ground 

 slag is applied directly to the soil without treatment with 



