Memoir upon Guano. 127 ^ 



Before giving an account of the experiments made upon 

 guano in order to discover it,s nature, it may not be improper 

 to communicate M. Humboldt's own opinion, as conveyed 

 in a note to the authors of this memoir. 



<* Guano is found in great abundance in the South Sea, 

 on the islands of Chincha, near Pisco ; but it exists also on 

 more southern shores and islands, such as Ilo, Iza, and 

 Arica. The inhabitants of Chancay, who make a traffic of 

 guano, so and return from the islands of Chincha in twenty 

 days. Each vessel has on board from 1500 to 2000 cubic 

 feet. A vanega costs at Chancay 14 livres, at Arica 15 livres 

 tournois. 



<' It lies in beds of 50 or 60 feet deep, which are wrought 

 like mines of iron ochre. These islands are inhabited hy an 

 immense quantity of birds, particularly of the ardea (ihe 

 heron) and the pboenicopterus (flamingo) kinds, which al- 

 ways pass the night on shore ; but it requires a period of 

 three centuries before their excrements increase to four or 

 five lines in thickness. Is guano a production caused by 

 changes which the globe has undergone, like coal or fossil 

 wood ? The fertility of the otherwise steril shores of Peru 

 is produced by the use of this substance, which is a staple 

 article of commerce. Fifty small vessels called gvaneros are 

 continually employed in searching for it, and transporting it 

 -to the main land ; and we may perceive the smell of it at a 

 <iuarter of a league's distance. The sailors, who are accus- 

 tomed to this amntoniacal odour, sufler no inconvenience 

 from it, but it caused us to sneeze violently on approaching 

 it. For the cultivation of mace, in particular, it furnishes a 

 most excellent manure. The Indians have taught this nje- 

 ihod to the Spaniards. If too much guano, however, is , 

 ritrown upon the mace, the root is burnt up, and destroyed. 

 Guano is extremely acidiliable; so that here we have a ma- 

 nure of hydrurel of azote^ while other manures are rather 

 hydrurets of -carbon." 



Guano has a reddish yellow colour; it is almost ta3teless, 

 but has a strong smell, which resembles at once that of castor 

 and valerian. It blackens iti the fire, exhaling a white smoke 

 and ail ammoniacal odour. 



Its 



