OXALATE OF AMMONIA IN GUANO. 247 



ments made to elucidate this point, by the General 

 Committee of the Agricultural Society of Bavaria, 

 which we shall hereafter have occasion to mention, 

 have shown that whilst the use of guano was found, in 

 many cases, to increase very considerably the produce 

 of corn and straw of a field, the application of an am- 

 moniacal salt containing an amount of nitrogen cor- 

 responding to that in the guano produced no perceptible 

 effect on the crop of the same cereal, grown in the 

 same year, upon another plot of the field, when com- 

 pared with the produce of a third unmanured plot of 

 the same field. 



Though the part which the ammonia in the guano 

 plays, in many cases, in increasing the produce, cannot 

 be questioned ; yet it is equally certain, on the other 

 hand, that in many other instances the fertilising action 

 of guano must be attributed principally to its other con- 

 stituents. 



If the ash of guano is compared with calcined bones, 

 or bone-earth, it is found that the difference between 

 the two is not very great ; yet an amount of bone-earth 

 containing the same proportion of earthy phosphate as 

 in guano, or even two to four times that quantity, has 

 not the same action as the latter manure. Even a mix- 

 ture of bone-earth with ammoniacal salts in sufficient 

 proportion to make the amount of nitrogen and phos- 

 phoric acid equal to that contained in the guano, though 

 more efficacious than bone-earth alone, has still a dif- 

 ferent action from guano. The great distinction be- 

 tween the two lies in the greater rapidity of the action 

 of the guano in the first year, and often even in the 

 course of a few weeks, whilst in the year after it is 

 barely perceptible ; that of the bone-earth, on the other 

 hand, is comparatively slight in the first year, but in- 

 creases in the following. 



The cause of this difference of action is the oxalic 

 acid in Peruvian guano, which often amounts to from 6 

 to 10 per cent. If guano is subjected to lixiviation, the 

 water dissolves sulphate, phosphate, and oxalate of am- 

 monia, which latter salt crystallises out abundantly 



