| Description | Davy shares details of the analysis of guano, describing its composition. He then describes an experiment made for the purpose of determining whether the oxalic acid [ethanedioic acid] existing in guano may not be formed from the lithic acid of urine, in consequence of the operation of the sun’s rays. The result of a comparative trial made with the urine of the white-headed Sea-Eagle (Haliaeetus leucogaster), in one instance kept in darkness, in the other exposed to bright sunshine for many successive days, afforded an answer in the affirmative. Whilst the urine of the Sea-Eagle, consisting chiefly of lithate of ammonia, kept in the dark, underwent no change, that exposed to light was materially changed, most of the lithate of ammonia had disappeared, its place was supplied by oxalate of ammonia, the peculiar odour of guano was acquired, and in part its brownish hue. From considering the composition of the lithic and oxalic acids, the author infers, that in the conversion of the one into the other, oxygen is absorbed; and, in confirmation, he mentions that although no change takes place when moist lithate of ammonia is exposed alone to a temperature of about 212°, it is otherwise if so treated when mixed with black oxide of manganese, in which case oxalate of ammonia is formed, and also some brown colouring matter, not unlike that of guano. He suggests that this colouring matter may appropriate to itself the excess of carbon and hydrogen, that is, such proportions of these substances in the lithic acid as are more than those required to form oxalic acid and ammonia.
Subject: Chemistry
Received 16 June 1844.
Written by Davy at The Oaks, Ambleside [Cumbria, England].
Whilst the Royal Society declined to publish this paper in full, an abstract of the paper was published in volume 4 of Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London [later Proceedings of the Royal Society] as 'On the action of the sun’s rays on lithic acid'. |