on the Nature and Properties of Albumen^ S^c. 17 



C. Hydrochloric acid removes the slight turbidity it pre- 

 viously possessed, and causes it to assume a lilac tint. 



D. Ammonia, by the assistance of heat, partly dissolves it ; 

 forming a gelatinous solution, becoming turbid when diluted 

 with water. 



E. Acetic acid produces a partial coagulation ; causing the 

 mucus to assume the appearance of a corrugated membrane, 

 floating in the acid. 



F. Infusion of galls produces a copious precipitate. 



G. A quantity being evaporated to dryness, left a gum-like 

 residue ; which, when carefully incinerated in a platinum cru- 

 cible, yielded a perfectly white ash, destitute of all traces of 

 iron : it turned turmeric paper brown, and partly dissolved 

 in acids with effervescence, demonstrating the presence of an 

 alkaline carbonate. 



Upon a review of these experiments, we find none of the 

 phaenomena hostile to the opinion of the presence of albumen : 

 indeed, some of them (B. C. F.) appear to indicate the pro- 

 bability of its existence. The action of acetic acid (E.) is quite 

 peculiar to that combination existing in mucus ; to which I 

 shall again have occasion to refer. 



2. When nearly limpid mucus possessing the above pro- 

 perties is kept for a few days exposed to the air, it becomes 

 turbid, and gradually lets fall a white cream-like deposit. 

 Some of this was collected and examined : it presented, under 

 the microscope, the appearance of numerous round particles, 

 which were readily recognised as coagulated or insoluble al- 

 bumen ; for they dissolved in hydrochloric acid, yielding a fine 

 lilac-coloured solution ; in nitric acid, with the aid of heat, 

 they formed a yellow fluid, becoming brown on the addition 

 of potass ; and with acetic acid they yielded a colourless so- 

 lution, from which ferrocyanide of potassium threw down a pale 

 yellow precipitate in the cold. 



3. Having thus proved this deposit to consist of albumen, a 

 most interesting question arises as to its source; for, as has 

 been already shown, (2) none of this principle could be ab- 

 solutely p7'0ved to exist in the mucus before exposure to air, 

 however much its presence might have been suspected. My 

 first suspicions were, that the carbonic acid of the atmosphere 

 had been the active agent, by combining with the substance 

 which previously held the albumen in solution : this appeared 

 to be probable, as some experiments, which it is unnecessary 

 to detail, seemed to countenance the idea of the existence of 

 albuminate of soda in mucus. I accordingly placed a glass 

 filled with the same limpid mucus under a jar of hydrogen 



Phil. Mag. S. 3. Vol. 13. No. 79. July 1838 C 



