VIII.] COMPOSITION OF PERUVIAN GUANO 233 



latterly been exported in large quantities ; it consists 

 of the phosphatic guanos derived from the Lobos 

 Islands, containing as much as 60 per cent, of calcium 

 phosphate and only from 2 to 3 per cent, of nitrogen. 

 In addition to these cargoes of varying composition 

 which are sold in the condition in which they arrive, 

 the importers make up a mixture to a standard com- 

 position with about 7 per cent, of nitrogen, which is 

 sold as equalised Peruvian guano. 



Peruvian guano, as imported, is a loose dry powder, 

 grey in the richer samples and becoming browner as it 

 grows more phosphatic. As a rule, it is friable and 

 may be sown by any manure distributor, but there 

 are found in it occasional fragments of slaty rock, 

 with a number of half-decayed feathers in the richer 

 specimens. It possesses a strong and characteristically 

 ammoniacal smell and an alkaline reaction due to the 

 presence of ammonium carbonate. 



The following detailed analysis, Table LXXIV., 



shows the composition of a sample of the Chinchas 

 deposit; it will be seen that the nitrogen is mainly 

 present in compounds soluble in water — uric acid, a 

 little urea, guanine, and ammonium salts, with a trace 

 of nitric acid. The phosphoric acid is also largely 



