GTJANO. 289 



mere y for the sake of the dung; the quantity yielded in this tinne 

 may be about a wagon-load. In the neighborhood of Lisle, this 

 manure is applied particularly in the cultivation of flax and tobacco. 

 According to M. Cordier, the dung of between seven hundred and 

 eight hundred pigeons is sufficient to manure nearly 2- acres of 

 ground. The dung of three hundred and twelve pigeons, therefore, 

 would sufl^ice for an acre. The value of pigeon's dung may be es- 

 timated from the large proportion of azote which it contains ; that 

 which I analyzed from }3echelbronn gave S] per cent, of this prin- 

 ciple, a result which ought not to excite surprise when it is known 

 that the white matter that appears in the excrements of birds, con- 

 sists of nearly pure uric acid. 'I'he manure of the hen-house is 

 nearly or quite as good as pigeon's dung. 



Guano is a manure of the same nature as pigeon's dung, and the 

 use of which, long familiar on the coasts of Peru, has lately extend- 

 ed to these countries, the article being now imported in large quan- 

 tities, both from the South American and African coasts. Guano 

 appears to be the result of the accumulation for ages of the excre- 

 ments of the sea-fowl, which live and nestle in the islets, in the 

 neighborhood of the great southern continents of the new and old 

 world. The mass in many places forms beds of between 60 and 70 

 feet in thickness. The principal places whence guano is obtained, 

 are the Chinche islands near Pisco ; but other deposites of the sub- 

 stance are known to exist more to the south, — in the islets of Iza 

 and Ilo, at Arica, and in the neighborhood of Payta, as 1 had an op- 

 portunity of ascertaining during my stay in that port. The inhab- 

 itants of Chinche are the principal traders in guano ; and a class of 

 small vessels, called Guaneros, are constantly engaged in carrying 

 the manure.* 



Fourcroy and Vauquelin were the first who fixed attention on the 

 nature of guano. The specimen which they examined was brought 

 to Europe by M. de Humboldt, and contained : Uric acid (0.25,) ox- 

 alate of ammonia, chlorhydrate of ammonia, oxalate of potash, 

 phosphates of potash and of lime, chloride of potassium, fatty matter, 

 and sand. 



Since this time Dr. Fownes has again analyzed guano. The 

 sample upon which he operated was of a light brown color and ex- 

 tremely offensive smell ; it yielded : 



Oxalate of ammonia i 



Uric acid \ 66.2 



Traces of carbonate of ammonia and organic matter j 



Phosphates of lime and of magnesia 29.2 



Phosphates and alkaline chlorides, and traces of sulphates 4.6 



100.0 



Another sample, deeper in color and without smell, contained : 

 Pure oxalate of ammonia, 44.6; earthy phosphates, 41.2 ; alkaline 

 Dhosphates, sulphates, and chlorides, 14.2=100. 



The composition of guano would confirm, were there any occasion 



* Humboldt, Annales de Chimie, vol. Ivi. p. 258. 

 35 



