Composition of Different Guanos.

The following is a list of the more common nitrogenous and phosphatic guanos which have been used in the past or are at present in use. Those printed in italics are still being worked. As their value depends on their nitrogen and phosphoric acid, these alone have been given. The percentages must be taken as mere approximations, as the quality of different cargoes from the same deposits varies very much. The table may be found useful for reference.

Nitrogenous Guanos.

Phosphoric} {Tricalcic
Nitrogen=Ammonia.acid} = {phosphate.
per cent. per cent.per cent. per cent.
Angamos20 24 5 11
Chincha14 1713 28
Ballestas12 1512 26
Egyptian11 1319 41
Guanape11 13— —
Macabi11 1312 26
Corcovado11 1315 33
Saldanha Bay 9 11 9 20
Ichaboe 8 10 9 20
Independence Bay 7 912 26
Pabellon de Pica 7 914 31
Punta de Lobos 4 515 33
Huanillos 6 718 28
Penguin 5 611 24
Patagonian 4 518 39
Falkland Islands 4 514 31

Phosphatic Guanos.

Phosphoric} {Tricalcic
acid} = {phosphate.
per cent. per cent.
Maracaïbo, or Monks42 92
Raza Island40 87
Curaçao40 87
Baker Island39 85
Starbuck38 83
Enderbury37 81
Californian35 76
Aves34 74
Fanning Island34 74
Howland34 74
Sidney Island34 74
Mejillones33 72
Lacepede Island33 72
Malden Island32 70
Sombrero32 70
Browse Island31 68
Huon Island28 61
Patos Island24 52
Jarvis Island20 44
Cape Vert11 24

NOTE VI. (p. 314).

It may be of interest to refer to a theory put forward by Liebig as to the action of oxalic acid in guano. This, he considered, had the effect of gradually rendering the insoluble calcium phosphate soluble, and giving rise to the formation of ammonium phosphate and calcium oxalate. Such an action would probably take place were the guano allowed to ferment by itself. We know, however, that when it is brought in contact with the soil-particles, all its soluble phosphate is converted into precipitated phosphate.

NOTE VII. (p. 326).

Analyses of Dung of Fowls, Pigeons, Ducks, and Geese.
(Storer's 'Agricultural Chemistry,' vol. i. p. 367.)