ALBUMEN. 333 



aqueous solution is heated (Scherer) ; for it does not separate in 

 flakes like pure albumen, but forms a white, almost gelatinous mass, 

 or simply gives rise, if the fluid is more or less diluted, to a 

 milky or only whitish opalescent turbidity. The alkaline reaction 

 of the fluid is more strongly marked after boiling, which proves 

 that at least a portion of the alkali must be separated from the 

 albumen on its coagulation. The liberated alkali combines with a 

 small portion of the albumen to form albuminate of soda, which 

 remains dissolved. This albumen, separated by coagulation, passes 

 however, in part, through the filter, and very soon clogs its pores. 

 On saturating the solution of albuminate of soda with acetic acid, 

 or some other organic acid, it will coagulate on being heated, like 

 pure albumen, into flakes that may be readily collected on the filter. 

 An albuminous solution, after being thus neutralised, is rendered 

 turbid when diluted with a large quantity of water (about twenty 

 times its own volume) ; a large portion of the albumen, poor in 

 salts and free from an alkali, being precipitated from the solution. 



This phenomenon is dependent upon the circumstance that the 

 albumen, freed from the alkali by acetic acid, is held in solution by 

 the salts, which, however, when strongly diluted, lose their solvent 

 power, and cause the gradual separation of the albumen. 



On treating this albuminate of soda with dilute alcohol, there is 

 a precipitation of albumen free from alkali and poor in salts ; whilst 

 another portion combined with more alkali remains in solution and 

 represents the true albuminate of soda, which we are now going 

 to consider. This precipitate dissolves only slightly in pure water, 

 but readily in aqueous saline solutions. 



A further addition of alkali to the normal albumen contained 

 in the animal fluids gives rise to an essential difference in its 

 properties. When the solution has been highly concentrated, it 

 yields, on being heated, a translucent jelly, almost insoluble in water, 

 and containing, according to my observations, 4'69 parts of 

 potash or 3'14 of soda to 100 parts of albumen free from salts. 

 On diluting the solution with water, it no longer yields this colour- 

 less jelly or any precipitate whatever, on being heated. The albumen 

 even appears entirely to have lost its coagulability, but such is not 

 the case, for when treated with an excess of alkali, it becomes con- 

 verted into the coagulated state even without the application of 

 heat ; for if the solution be neutralised with some acid that does 

 not ordinarily precipitate albumen, (as acetic acid, tartaric acid, or 

 tribasic phosphoric acid), albumen is separated in a coagulated 



