TRANSACTIONS OF THE SECTIONS. 55 



broken at the instant of their production : if, however, a pot in the act 

 of crystallizing is suffered to remain at rest a few moments until a 

 crust forms on its surface, on carefully withdrawing a portion of this 

 crust, it is found on its under side to exhibit a distinctly crystalline ap- 

 pearance, proving that the solid particles, which are merely this crust 

 broken to pieces, are the result of a rapid crystallization. 



This reasoning the author endeavoured to confirm by illustrations 

 drawn from other chemical processes, and mentioned experiment to 

 ascertain the degree in which, by a cautiously regulated heat, silver 

 may be separated from lead by the process of eliquation. Pieces of 

 lead were most cautiously heated till a few drops of fused metal oozed 

 out from their pores ; this was found to be slightly richer in silver than 

 the original mass. In these experiments, as in the draining of the cry- 

 stals, the separation is effected by the difference of fusibility between 

 pure lead and lead containing silver, aided, no doubt, by the tendency 

 of pure lead, in that state of semi-fluidity, to assume a crystalline form. 



Observations on some of the Products obtained by the Action of Nitric 

 Acid on Alcohol. By Golding Bird, M.I).-, F.L.S., G.S., ^c. 

 Lecturer on Natural Philosophy at Guys Hospital, London, ^c. 



In this paper the author alluded more particularly to the nature of 

 the substances produced simultaneously with hyponitrous ether during 

 the preparation of the spiritus etheris nitrici of the London Pharma- 

 copeia, which products have been usually stated to be malic, oxalic, 

 acetic, and carbonic acids, together with a substance mentioned by 

 Thenard as " tres facile a charbonner," in addition to the hyponitrous 

 ether (4 C, 5 H, O + N, 3 O). Taking advantage of the residue left 

 after preparing a large quantity of sp. eth. nit. in the pharmaceutical 

 laboratory of Guy's Hospital, Dr. Bird instituted a series of experi- 

 ments enumerated in his paper, from which he was induced to believe 

 that oxalic acid was by no means a necessary product, and that it is 

 not generated until aldehyd begins to ajjpear in the distilled fluid. As 

 the paper is published entire in the Philosophical Magazine for this 

 year, it is unnecessary to do more than give the result of Dr. Bird's 

 investigations : 



1 . That in the preparation of sp. etheris nitrici, as long as the latter, 

 with alcohol only, distils over, no oxalic acid is produced ; an acid ap- 

 parently identical with the oxalhydric alone appearing in the retort. 



2. That on continuing the distillation beyond this point, the free 

 nitric acid in the retort acting on the oxalhydi-ic acid, generates oxalic 

 acid. 



3. That during the action of nitric acid on alcohol in the cold, as in 

 Dr. Black's process for the preparation of hyponitrous ether, acetic 

 acid is produced, instead of, or in addition to, oxalhydric acid. 



4. That aldehyd is, as has been long known, produced by the action 

 of nitric acid on alcohol, but that it is not formed in any quantity, or at 



