Intelligence and Miscellaneous Articles* 473 



other fish-bones occur frequently, as well as remains of plants and 

 some seed. 



The guano had a strong urinous smell and a faintly saline taste. 

 16 oz. of the pulverulent mass in its moist state afforded on solution 

 in caustic potash and precipitation with muriatic acid, 7 oz. 2 drms. 

 of a yellowish-brown coloured crystalline hydrate of uric acid 

 = 37 per cent, anhydrous uric acid. 



200 grs. of a compact fragment with very few seams of clay, gave, 

 on being similarly treated, 118 grs. or 59 per cent, of anhydrous 

 uric acid. The residue of these experiments consisted for the 

 greater part of clay, which readily subsided, probably on account of 

 the earthy phosphates contained in it. 



From the occurrence of so few organic remains, and from the in- 

 terposition of the argillaceous masses between the layers of urate of 

 ammonia, it is evident that the guano in question cannot have been 

 deposited by the birds in the state in which it occurs at present ; 

 the coating of urate of ammonia, which adheres so firmly to the 

 seams of clay, decidedly shows that water must have acted some part 

 at the formation of this deposit. 



Let us suppose a clayey shore, which is flooded at high tide and 

 left dry at ebb, and behind it a lake to which the tide rises, and 

 flocks of sea-birds which visit the coast at the time of low water ; 

 all the requisite conditions are given. Fish and other marine ani- 

 mals, left by the tide, attract the birds, which, in taking their food, 

 at the same time loosen the soil. Meantime a tropical sun dries and 

 breaks up the soil ; the tide returns, and carries these loose masses 

 of clay, and the excrements deposited on them, into the basin. In 

 their progress a process of lixiviation takes place ; the lighter organic 

 remains, which have not time to subside, are carried away by the 

 effluent water, while the heavier urate of ammonia and fragments of 

 clay subside. At some depth the bottom of the basin is not disturbed 

 by the flood, and here a solution of urate of ammonia may be formed, 

 which subsequently, on drying, covers the layers of clay with a 

 white coating, and serves to unite the pulverulent urate of ammonia 

 and loose clay. The amount of soluble constituents in the guano 

 (20 per cent.) is not opposed to this view, for if the urine of these 

 birds is secreted, like that of serpents, in a concrete form (containing 

 therefore solid urate of ammonia), it would be impossible for the 

 salt water to deprive it of much of its soluble constituents during 

 its transfer, and its rapid subsidence in the basin would prevent sub- 

 sequent extraction. 



Now it is quite evident that the African guano has been exposed 

 to entirely different conditions to that of the Peruvian just described ; 

 for while this contains the enormous amount of 59 per cent, uric 

 acid, scarcely traces of it occur in the former, it having undergone 

 total decomposition. Moreover, the amount of soluble constituents 

 in the African guano (above 60 per cent.) entirely excludes all idea 

 of its having been subjected to any such lixiviating process as that 

 supposed by Dr. Fritzsche. 



We may, in conclusion, venture a few words with respect to the 



