130 SOILS AND FERTILIZERS 



will keep if stored in a cool place, and may be applied 

 directly to the land or added to a compost heap." 



The price per pound of nitrogen in the form of 

 dried blood can be determined from the cost and the 

 analysis of the material. A sample containing 9 per 

 cent, of nitrogen and selling for $20 per ton is equiva- 

 lent to 11. 11 cents per pound for the nitrogen (2000 X 

 0.09 = 180. $20.00 -j- 180 =11.11 cents). 



152. Tankage is composed of miscellaneous refuse 

 matter as bones, trimmings of hides, hair, horns, hoofs, 

 and some blood. The fat and gelatin are, as a rule, 

 first removed by subjecting the material to superheated 

 steam. This miscellaneous refuse, after drying, is 

 ground and sometimes mixed with a little slaked lime 

 to prevent rapid fermentation. 



Tankage contains less nitrogen but more phosphoric 

 acid than dried blood. Owing- to its miscellaneous 

 nature, it is quite variable in composition, as the fol- 

 lowing analyses of tankage from the same abattoir at 

 different times show. 13 



First year. Second year. Third year. 



Moisture 10.5 9.8 10.9 



Nitrogen 5.7 7.6 6.4 



Phosphoric acid 12.2 10.6 11.7 



As a general rule, tankage contains from 5 to 8 per 

 cent, of nitrogen and from 6 to 14 per cent, of phos- 

 phoric acid. It is much slower in its action than 

 dried blood, and supplies the crop with both nitrogen 

 and phosphoric acid. Tankage is a valuable form of 



