Oil Guano. 



311 



fermentation contains the most of them, leads to the belief that 

 they are fitted to promote vegetation. 



The fresh guano is more valuable, chiefly because it contains 

 more of this uric acid in an undecomposed state. We have no 

 analyses of the recent droppings of any of the birds which frequent 

 the shores of Peru ; they would probably be found to differ in 

 some degree, not only with the species of bird, but also with the 

 kind of fishes on which at different seasons of the year they were 

 found to prey. We possess analyses, however, of the excretions 

 of other birds which live chiefly upon fish, from which we are 

 enabled to form an opinion as to what the recent guano is likely 

 to be. Thus Dr. Wollaston found those of the gannet (Pelicanus 

 bassanus), when dry, to contain little else but uric acid, while in 

 those of the sea-eagle Coindet found — 



Solid Excretions. Liquid Excretions dried. 



Per Cent. _ Per Cent. 



Ammonia .... 9*2 Uric acid . . . .59 



Uric acid . , . . 84 • 65 Earthy and alcaline phosphates, sul- 

 Phosphate of lime . . . 6'13 phates, and chlorides . .41 



100 100 



If we compare the first of these results of Coindet with the 

 constitution of the guano as it is imported into England, we cannot 

 fail to be struck with the degree of decomposition which the latter 

 must have undergone — supposing it to have originally resembled 

 the solid excretions of the sea- eagle. The quantity of phos- 

 phate of lime in the latter, 6*13 per cent., is unusually large for 

 the excrement of a bird; but if we suppose the recent guano 

 in its dry state to have contained quite as much, it would require 

 500 lbs. of the latter to give the quantity of phosphate (29*3 lbs.) 

 contained in 100 lbs. of a quality such as the one portion I 

 examined, and 700 lbs. to yield the quantity of phosphate 

 (44*4 lbs.) contained in the other. In other words, from ^ 

 to Y only of the original organic animal ^natter remains in the 

 guano, as it is imported into England. It probably retains even 

 less, since it has unquestionably absorbed from the air a con- 

 siderable portion of moisture not supposed to be present in the 

 droppings when recent and carefully dried. 



It is easy to see therefore why the recent guano should bring 

 so much higher a price on tho coast of Peru ; why the ancient 

 Peruvians should have so carefully collected it, and should so 

 religiously have preserved the sea-fowl from destruction or dis- 

 turbance ; and why they should have left the ancient accumula- 

 tions comparatively undisturbed ; — to be searched for and ex- 

 cavated in these after- times when the produce of the living birds 

 has become less abundant or is less carefully collected and 

 preserved.* 



* The coraparative value of the recent droppings of birds is shown by 



