the Formation of Guano. 229 
moniacal odour, mixed with one slightly putrid, and to con- 
tain some oxalate of ammonia, as was shewn both by the 
microscope and by chemical examination, but in proportion- 
ally less quantity than in that under the influence of light. 
In the 3d experiment, that in which the urine was confined 
over mercury, in a limited portion of atmospheric air ($ cubic 
inch), the volume of the air was little changed, but its com- 
position greatly. At the commencement of the experiment, 
it consisted, as atmospheric air, of 21 oxygen and 79 azote ; 
at the termination, it was found composed of 64 carbonic 
acid (so much was absorbed by lime-water), and of 36 azote. 
The solid urine had no sensible smell of ammonia; it afforded, 
however, indications of the presence of oxalate of ammonia, 
but in a very minute quantity, merely a trace, and without 
any smell, at least that I could perceive, of the volatile 
alkali. 
The result of the last experiment, namely, that in which 
pure lithic acid in its granular state was exposed to light, 
atmospheric air not being excluded, was altogether negative: 
its colour was not altered, nor its granular form; it had 
acquired no smell of ammonia; and, carefully tested for oxa- 
late of ammonia, not a vestige of this salt could be detected. 
It may be mentioned, that it was obtained by precipitation 
by dilute muriatic acid from a solution of lithate of ammonia 
in water. 
From the results of these experiments, and considering the 
composition of the lithic and oxalic acids, the former con- 
taining the elements of the latter, and of ammonia, but with 
excess of carbon, may it not be inferred, that though the 
light of the sun is not essential to the conversion of the 
lithate of ammonia into the oxalate, it promotes and accele- 
rates the change; and, further, that the presence of atmo- 
spheric air is required for the change, the excess of carbon 
uniting with the oxygen, and separating in the form of car- 
bonic acid gas? And, in confirmation of this, it may be 
mentioned, that though the urine of the sea-eagle alone, 
moistened with water, subjected many hours to the tempe- 
rature of 212°, yielded no oxalate of ammonia, it afforded a 
