Blood 



quantities. Being formed under shelter, the ferti- 

 lising materials have not been washed away by rain, 

 but in some places infiltration has caused a partial 

 loss, and then, the humidity favouring fermentation, 

 part of the nitrogen has been given off in the form 

 of ammonia. This explains the difference in their 

 quality, and is a reason why they should only be 

 bought on analysis. In any case, they are a very 

 active manure, better generally than modem guanos. 

 Here is their average composition : 5 per cent, 

 nitrogen ; 9 per cent, phosphoric acid. 



They are found in many places — Cuba, Venezuela, 

 Algeria, Spain, Sardinia, Madeira, and elsewhere. 



Blood. 



Animal blood, being the vehicle of all the materials 

 assisting in the constitution of the body, contains all 

 the elements of which the body is composed — that 

 is 80 per cent, water, 2-5 to 3 per cent, organic 

 nitrogen, 0'55 per cent, of phosphoric acid as tri- 

 calcic, and 0-5 per cent, potash [K2O]. Consequently 

 it is chiefly rich in nitrogenous matter. It can be 

 employed in a fresh state as long as it is not spread 

 in large quantities on growing plants, which it would 

 burn. 



As a matter of fact it is rarely employed in a 

 liquid state, because it cannot always be used 

 immediately, and if kept, the nitrogenous organic 

 matter becomes tainted and emits a nauseating 

 smell. When it is obtainable in small quantities it 

 is better to absorb it in some kind of neutral material, 

 or preferably to add it to leaf compost, when it will 

 have a real value. 



115 



