ANIMAL MANURES. 1 29 



190. In guano, we find all the inorganic materials which 

 existed in the food of the birds by which it has been deposited, 

 for, by a peculiarity in the sti'ucture of bu'ds, both the liquids 

 secreted by the kidneys and the solid contents of the bowels 

 are discharged from the same apertm-e, and thus both the 

 soluble salts which had been taken into the circulation, and 

 the undigested matters of the food are contained in these 

 deposits. In countries like Peru, where rain seldom falls, 

 the soluble parts of the excrements di-ied up by the wai-m 

 sun, remain for centuiies, and the substances containing 

 nitrogen (uric acid, &c.), are not decomposed into volatile 

 compounds, so that in the best preserved samples of Peruvian 

 guano the smell of ammonia is scarcely to be perceived, while 

 in samples of the manm*e bought from other places not so 

 favourably situated for its pj-esei-vation, the alkalme salts 

 have neaily disappeared, and a strong pungent ammoniacal 

 odour is evolved by the decomposing nitrogenised matters, 

 thus while genuine Peruvian and Bolivian guanos yield in 

 general from 10 to 16 per cent of ammonia, the guano brought 

 from Patagonia consists chiefly of the insoluble Phosphates 

 (53), and aflfords only about 3 or 4 per cent of ammonia. 



191- The composition of guano has been studied by ex- 

 perienced chemists, both on the continent and in this countr}-. 

 The most complete analyses which have been published, are 

 those of Mr. Deuham Smith, communicated to the Chemical 

 Society. The following is the composition of a sample of 

 Penivian guano, said to be of very superior quality ; 1 00 parts 

 contained — 



Water , 21-510 



Organic matter and, combined water 12 296 



Potash '. 1-144 



Soda 3-430 



Ammonia 6-434 



Lime 15-3o(» 



Magnesia 0-764 



Muriatic acid 2-414 



Sulphuric acid 2-106 



Oxalic acid 12-850 



Phosphoric acid 16-328 



Uric acid 2*308 



Humus 2-OGO 



Sand I'CAH 



Loss •36l* 



100-000 



