296 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



Dried blood comes from the large slaughtering establishments, 

 and is of two kinds, red and black. The red dried blood results 

 from drying at the temperature of boiling water, at which tem- 

 perature it does not char. The black dried blood is dried at a 

 higher temperature, and decays more slowly. Dried blood is one 

 of the most concentrated organic nitrogenous fertilizers. It con- 

 tains about ii per cent, nitrogen. It decays quickly in the soil. 



Dried meat or meat meal is obtained from rendering establish- 

 ments, where the different portions of dead animals are variously 

 utilized. It is rich in nitrogen, and, like blood, decays rapidly. It 

 also comes from slaughter houses where the waste meat is kept 

 separate from the tankage. 



Dried fish or fish scraps come from two sources : first, the offal 

 of fish canneries, and second, the fish pomace resulting from the 

 extraction of oil from Menhaden or other fish. The latter pro- 

 duct is more uniform than the former, containing 7 to 9 per cent, 

 of nitrogen and 6 to 8 per cent, phosphoric acid. Fish unfit for 

 eating may be caught, the oil extracted, and the residue prepared 

 into fish guano. 



Tankage consists chiefly of the dried animal wastes from the 

 large slaughtering establishments; to some extent it comes from 

 the garbage plants of large cities. It is very variable in com- 

 position, since it contains all parts of the carcass which cannot be 

 used for other purposes the bones, tendons, flesh, etc. Tankage 

 varies so much that it is always sold in the trade on the basis of 

 its composition, and each shipment is subjected to analysis. It 

 contains 5 to 10 per cent, nitrogen and 6 to 15 per cent, phosphoric 

 acid. As a rule the fat and gelatine are removed by treatment 

 with super-heated steam. Garbage tankage is less valuable than 

 slaughter house tankage. It contains approximately 3 per cent, 

 nitrogen and 1.2 per cent, each of phosphoric acid and potash. 



Cottonseed meal is prepared by grinding the cake left from 

 pressing the oil from cottonseed kernels. It is one of the best 

 vegetable fertilizers. It is an excellent cattle feed, and its most 

 economical use takes advantage of both its feeding and its 

 fertilizing values, by feeding the meal and saving the manure. It 



