GUANO. 179 



begins to act instantaneously^ when applied to moist 

 lands. In good guano, nearly one half consists of 

 salts of ammonia, whereas inferior varieties often 

 exhibit mere traces of them. At the present day, 

 guano, notwithstanding its high price, is still the 

 cheapest source for procuring ammonia that is open 

 to the German farmer ; for a pound of this sub- 

 stance in bird manure may be reckoned at one shil- 

 ling, whilst the ammoniacal salts to be purchased in 

 the market cost at the lowest price from 1^. l\d. to 

 2s. Id. As long, therefore, as German fields are 

 brought to a high degree of productiveness by means 

 of ammonia, and as long as we possess no cheaper 

 means of obtaining it, so long must guano be ad- 

 vantageously employed as a powerful agent in the 

 improvement of German agriculture. 



At ordinary temperatures, the ammoniacal salts 

 contained in guano are not volatile, since the acids 

 present, which are generated at the same time with 

 the process of putrefaction (humus acid, oxalic acid, 

 etc.), operate in the same way as sulphuric acid in 

 fixing the ammonia. Hence it need not be appre- 

 hended, that guano will lose greatly in strength by 

 long-continued preservation. Upon being heated, 

 on the other hand, the substances fly off.* 



Next to nitrogen or ammonia, phosphoric acid 



* This evidently refers to guano packed for transportation ; if well 

 secured in tight barrels, it will travel any distance without material 

 depreciation. On this subject see note on a succeeding page. — 

 J. E. T. 



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