ALBUMEN. 



89 



One hundred parts of dried white of egg, 

 subjected to destructive distillation, yielded 

 carbonic acid, carburetted and sulphuretted 

 hydrogen, prussic acid, carbonate of ammonia 

 partly in solution and partly sublimed, stinking 

 volatile oil, and 14.9 of spongy difficultly com- 

 bustible carbon, which, by incineration, left 

 2.21 of ash composed of carbonate of soda, 

 phosphate of soda, and phosphate of lime, 

 (Hatchett.) 



Nitric acid, dropped into a solution of albu- 

 men, forms a white, flaky precipitate, which is 

 more or less abundant according to the state 

 of dilution of the solution, and which is soluble 

 in ammonia and potash. When coagulated 

 white of egg is kept for some weeks in very 

 dilute nitric acid, it acquires a yellow colour, 

 and if digested in boiling water it dissolves, 

 and has acquired the properties of gelatine, 

 and is precipitated by tan and muriate of tin. 

 Hatchett.)* Cold nitric acid sp. gr. 1.25, 

 gradually tinges coagulable white of egg of a 

 yellow colour, dissolving a little of it, and 

 forming malic acid, with the evolution of nitro- 

 gen ; its surface becomes tallowy, and in 

 twenty-four hours it falls into a pale yellow 

 powder, which is acid and composed of nitric, 

 nitrous, and malic acids with albumen ; when 

 thoroughly washed with water, it becomes more 

 neutral and of an orange colour, still reddening 

 litmus, and remaining insoluble in water, but 

 soluble in caustic potash .f When coagulated 

 white of egg is digested in hot nitric acid, 

 nitrogen, nitrous gas, carbonic acid, and prussic 

 acid are formed, and a dark yellow solution 

 obtained, which is precipitated by the addition 

 of water and ammonia, and which contains 

 malic and oxalic acids, bitter matter, and fat. 

 (Hatchett.):!: 



Sulphuric acid is a less powerful precipitant 

 of albumen than nitric acid. Dilute sulphuric 

 acid dropped into an aqueous solution of 

 albumen occasions a precipitate which is so- 

 luble in excess of acid ; ferrocyanate of po- 

 tassa throws it down. When coagulated albu- 

 men is digested in sulphuric acid, very slightly 

 diluted, it yields a deep crimson solution . Coa- 

 gulated serum digested in sulphuric acid diluted 

 with six parts of water, converts it into acid 

 sulphate of albumen, which, when edulcorated 

 with cold water, becomes more neutral, and 

 is soluble in warm water, forming a gelatinous 

 solution, which is precipitated by sulphuric, 

 muriatic, and nitric acids, and by the alkalies. 

 (Berzelius.)H Coagulated white of egg digested 

 in hot sulphuric acid becomes carbonized 

 without forming artificial tan. (Hatchett.) 



When a solution of recently fused phosphoric 

 acid (pyro-phosphoric acid) is added to solution 



* Phil. Trans. 1799. 



t Berzelius Lehrbuch der Thier. Chemie, p. 38. 

 Wb'hler's Translation. Dresden, 1831. 



* Phil. Trans. 1799. 



According to Raspail, when sugar is previously 

 dissolved in the sulphuric acid, the albumen is co- 

 loured purple, which is deeper in proportion as the 

 acid and sugar are in greater quantity. 



|| Lehrbuch dcr Thier. Chemie. 



of albumen, it occasions an abundant pre- 

 cipitate : the acid gradually loses this property, 

 and again acquires it by fusion and ignition. 

 (Berzelius.) 



Muriatic acid occasions a precipitate in al- 

 buminous solutions, and entirely throws down 

 the albumen when aided by heat; but the 

 precipitate is soluble in excess of acid, and 

 in ammonia and potassa. A muriated albu- 

 men may be formed in the same way as the 

 sulphate. (Berzelius.) Coagulated egg-albu- 

 men digested in muriatic acid gradually ac- 

 quires a purple colour. (Hatchett.) Albumen 

 which has been precipitated by muriatic acid, 

 often becomes reddish when collected and ex- 

 posed upon a filter. 



When coagulated seralbumen is digested 

 in acetic acid, it becomes soft and transparent, 

 and, aided by a gentle heat, dissolves with the 

 evolution of a little nitrogen. This solution 

 is precipitated by the alkalies, but a slight excess 

 again renders it clear : it is also precipitated by 

 sulphuric, nitric, and muriatic acids, and by 

 ferrocyanate of potassa. When this acetic so- 

 lution of albumen is evaporated, it leaves a 

 transparent sour residue, soluble in warm water 

 acidulated by acetic acid. (Berzelius.) 



Albumen is slowly soluble in liquid ammo- 

 nia. In solution of potassa it becomes gelati- 

 nous, and yields a pale yellow green solution, 

 precipitable by acids and alcohol, and by acetic 

 acid. Heated in liquid potassa, albumen 

 evolves ammonia. 



Alcohol and ether coagulate ovalbumen, but 

 pure ether (free from alcohol) does not co- 

 agulate seralbumen. (Gmelin.) When serum 

 is shaken with ether, it soon separates upon 

 the surface, holding fatty matter in solution. 

 (Gmelin.) Coagulated serum digested in al- 

 cohol or ether yields a solution of fatty 

 matter. 



Coagulated ovalbumen, when long boiled in 

 water, becomes bulky and falls into pieces, and 

 a small portion is dissolved : the filtered so- 

 lution, evaporated at 212, leaves a pale brown 

 film, and is alkaline ; it is rendered turbid by 

 mineral acids, acetic acid, and tincture of 

 galls, and by many metallic salts. 



When albumen which has been cautiously 

 dried at a low temperature (without coagula- 

 tion) is triturated with four parts of water, 

 it yields a solution resembling fresh al- 

 bumen. 



A solution of the white of an egg in a pint 

 of water occasions no precipitate in lime, bary- 

 tic or strontia water, nor in solution of sulphate 

 of lime. Some of the neutral salts render 

 it more or less turbid, and it is copiously 

 precipitated by solution of alum. Nitrate, 

 acetate, and subacetate of lead are precipitated 

 by albuminous solutions. One part of fresh 

 ovalbumen in 2000 of water, or one of dried 

 albumen in 10,000 of water is rendered turbid 

 by subacetate of lead. A four-hundredth part 

 of liquid, or a two thousandth of solid albumen 

 is precipitable by corrosive sublimate. (Bos- 

 tock.) The precipitate is blackened by potassa, 

 and is probably a compound of muriate ofalbu- 



