ALBUMINOUS COMPOUNDS. 65 



obtained in a nearly pure state by very simple means. These two forms of it, 

 however, are not precisely identical; indeed, it appears from recent inquiries 

 that striking differences are produced in albumen, not merely by the presence 

 of some other body, such as an alkali or a salt, but by the different proportions 

 in which this occurs; and hence it is that various and contradictory statements 

 have been made, in reference to the properties of this substance. The follow- 

 ing are the facts of most physiological interest. In the before-mentioned 

 animal fluids, as well as in several others, Albumen exists in its soluble form, 

 but not in an isolated state ; for it is united with soda as an acid to its base, 

 and thus may be formed a basic, neutral, or acid albuminate of soda. The 

 basic compound, which contains about 1 per cent, of soda, and gives a 

 slightly alkaline reaction, is the one which ordinarily presents itself in normal 

 blood, as well as in the egg; but diseased blood (as first ascertained by Scherer) 

 very frequently contains a neutral albuminate, the characteristic of which is, 

 that its solution becomes turbid on the simple addition of water ; and it has been 

 shown by Lehmann that this occurs normally in the blood of the hepatic and 

 splenic veins, that of the former having been deprived of a portion of its alkali 

 whilst passing through the liver, and that of the latter having received an 

 additional charge of its acid in the splenic parenchyma. The ordinary basic 

 albuminate of soda, or sodo-albumen, is far more soluble in water than is pure 

 albumen, which, indeed, when entirely separated from all other substances, is 

 probably not soluble at all. It differs from pure albumen, moreover, in the 

 mode in which it coagulates on the application of heat; for whilst the latter 

 separates in flakes, sodo-albumen forms a white gelatinous mass, or, if the fluid 

 be much diluted, makes itself apparent only by a milky or opalescent turbidity. 

 The alkaline reaction of a solution of sodo-albumen becomes more marked on 

 boiling, which indicates that at least a portion of the alkali must be separated 

 from the albumen on its coagulation; and according to Prof. Liebig (op. cit. p. 

 387, note), a new compound of albumen with phosphoric acid and lime is then 

 probably formed. A moderately strong solution of pure albumen in water be- 

 comes turbid at 140, becomes completely insoluble at 145, and separates in 

 flakes at 167; when excessively diluted, however, no turbidity can be produced 

 by a less heat than 194 ; and coagula will only separate after it has been boiled a 

 considerable time. After having been dried in vacuo, however, or at a temperature 

 below 120, Albumen may be heated to 212 without passing into the insoluble 

 condition. 1 Albumen may be precipitated from an aqueous solution by diluted 

 alcohol; but it does not pass into the insoluble form, unless a large quantity of 

 strong alcohol be added. It is also precipitated by creosote. Albumen is con- 

 verted into the insoluble form by most acids; but it is not precipitated by the 

 mineral acids, unless they are added in excess; and the organic acids, with the 

 exception of the tannic, do not throw it down. It is converted into the insolu- 

 ble form by alkalies, but is not precipitated by them, being held up by their 

 presence. The greater number of metallic salts precipitate albumen, which 

 generally passes into the insoluble state, and enters into combination, either 

 with the basic salt itself, or with its acid and its base separately ; one of these 

 salts, the albuminate of the chloride of mercury, is of much interest, as being 

 that which is produced by the mixture of a solution of albumen with one of 

 corrosive sublimate. The following is the composition of Albumen, according 

 to the most recent analyses of two eminent chemists. 



1 The fact that dry Albumen may be heated to a much higher temperature, without 

 passing into the insoluble form, than Albumen in solution can be, is of much interest, in 

 relation to the experiments of Doyere and others upon the tenacity of life of the Tardi- 

 grade tribe of Rotifera ; for it has been found that, when completely desiccated, the bodies 

 of these animals might be exposed to a heat of 250, without the destruction of their 

 vitality. See "Princ. of Phys., Gen. and Cornp.," Am. Ed., g 65. 



