408 ORGANIC CHEMISTRY. 



coast of South America. In these haunts of the heron 

 flamandj and other sea-fowl, it is accumulated, in some 

 instances, to the depth of a hundred feet. The de- 

 posit is usually in smaller quantity, but amounts in the 

 aggregate to millions of tons. The material was em- 

 ployed as a fertilizer by the natives of Peru and Chili, 

 long before its introduction into England or the United 

 States for the same purpose. 



1024. DIFFERENT VARiETiES.-The qual- 



Whatiisaid ... ... 



of different ity of guano differs materially, according 

 to tlie source fr m which it is derived. 



The ammoniacal salts, on which its agency 

 as a fertilizer principally depends, being soluble in 

 water, the product of moist climates is of comparatively 

 little value. The best is obtained from the coast of 

 Peru, where rain seldom or never falls. The African, 

 Patagonian and other varieties, are much inferior. 



In what does 1025 ' AGRICULTURAL VALUE. The ag- 



theagricui- ricultural value of guano lies principally 



tural value . . 



of guana m the ammonia and phosphate of lime 

 depend? which it is capable of yielding to plants. 



These constitute, in the best varieties, about one-third 

 of the whole weight. Part of the ammonia is ready 

 formed, and part is produced in the subsequent change 

 which the nitrogenous matter of the guano experiences 

 in the soil. The latter may be produced immediately 

 by a chemical process, and its quantity accurately 

 determined. In estimating the value of guano, it is 

 customary to record the quantity of this potential am- 

 monia, as if it were an existing constituent. 



