292 
On the Analysis of Guano. 
his paper on guano, in the 3rd part of the 2nd volume of the Journal 
of the Royal Agricultural Society of England, are as follows : — 
Ammonia ....... 7*0 
Uric acid • . . . . . . 0'8 
Water and carbonic and oxalic acids, &c., ex- 
pelled by a red heat . . . . 51"5 
Common salt, with a little sulphate and phosphate 
of soda . . . . . . 11 "4 
Phosphate of lime, &c 29-3 
100-0 
The specimen of guano represented by this analysis must have been 
far advanced in decomposition, as shown by the very scanty portion of 
uric acid ; and must have been originally impure, from the large pro- 
portion of common salt, of which I have not found above 3 or 4 per 
cent, in any of the genuine guanos which I have had occasion to analyze. 
In another sample, Professor Johnston found 44*4 of phosphate of lime, 
with a little phosphate of magnesia, and carbonate of lime. These re- 
sults resemble, to a certain degree, those which I have obtained in ana- 
lyzing several samples of Chilian and African guanos, especially in the 
predominance of the earthy phosphates. The proportion of ammonia 
which can be extracted by the action of hydrate of soda and quicklime, 
at an elevated temperature, is the surest criterion of the soundness of 
the guano ; for by this process we obtained not only the ready-formed 
ammonia, from its several saline compounds, but also the ammonia pro- 
ducible from its uric acid, and undefined animal matter. These two 
latter quantities have been hitherto too little regarded by most analysts, 
though they constitute the most durable fund of azote for the nutrition 
of plants. Uric acid, and urate of ammonia, which contains 10-llths of 
uric acid, being both nearly insoluble in water, and fixed at ordinary 
temperatures, continue to give out progressively to plants in the soil, the 
azote, of which they contain fully one-third of their weight. Under the 
influence of oxygen and a certain temperature, uric acid passes through 
a very remarkable series of transformations ; producing allantoin, urea, 
and oxalic acid, which eventually becomes carbonic acid. These changes 
are producible immediately by the action of boiling water and peroxide 
of lead. From these metamorphoses we can readily understand how so 
much oxalate of ammonia and of lime is reported in many analyses of 
guano, though none, I believe, is to be found in the normal state, as it is 
occasionally imported from the Chincha Islands and Bolivia; nor were 
any oxalates found in the dung of the gannet, as analyzed by Dr. Wol- 
laston, or of the sea-eagle, according to the following analysis of Coindet: 
— ammonia, 9 '21 percent.; uric acid, 84 "65; phosphate of lime, 
6*13= 100. The Peruvian sea-fowl, by feeding exclusively on fish, 
would seem to swallow a large proportion of earthy phosphates ; since, 
in the purest guano that has come in my way, I have found these salts 
to amount to from 12 to 15 per cent. 
Dr. Von Martins proposes to use the degree of solubility of the guano 
in water as a good criterion of its quality ; but this is a most fallacious 
test. Sound guano contains from 20 to 25 per cent, of insoluble urate 
of ammonia ; nearly as much undefined animal matter, along with from 
