38 



ALBUMEN. 



Account of Ceylon. Lond. 1681. Labillardiere, 

 Voyage. Par. 8. Lawrence's Lectures. Lond. 1819. 

 Le Cat, Traite de la Pcau. Arnst. 1765. Lowthorpe's 

 Abridg. of Phil. Trans. (2d. ed.) Lond. 1716. Lu- 

 ciarats a Gnevio. Amst. 1687. Ludolf, Hist. jEthiop. 

 comment. Franc. 1691. Mansfeldt, in Journ. 

 Compl., t. xv. Maupertuis, Venus Physique. Haye. 

 1746. Monge, in Journ. Phys. pour 1782. Pauw, 

 Recherches sur les Americains, Lond. 1760. Per- 

 cival's Account of Ceylon. Lond. 1803. Ditto, in 

 Irish Trans., v. iv. Plinivs, Hist. Nat. a Valpy. 

 Lond. 1826. Ditto, a Lemaire. Par. 1827. Ditto, 

 lib. vii. . . xi., a Cuvier. Par. 1827. Pline, Hist. 

 Nat. par Ajasson (trad.) Par. 1829. Pomponius 

 Mela, a Gronovio. L. B. 1782. Prichard, in Cy- 

 clop, of Pract. Med., " Temperament." PtolemcEus, 

 Geographia, a Bertio. Amst. 1618. Rayer, Traite 

 des maladies de la Peau. Par. 1826. Raynal, Hist, 

 des Indes. Neuch. 1785. Renuuldin, in Diet, des 

 Sc. Med., " Albino." Ribeyro, Hist, ^de Ceylon. 

 Trev. 1701. Rush, in Amer. Trans., v. ii. and iv. 

 Sachs, Hist. Nat. duor. LeucEethiopum. 1812. St. 

 Hilaire, ( Isid. ), Anomalies de 1'Organization. Par. 

 1832. ; Ditto, in Diet. Class. d'Hist. Nat., " Mam- 

 miferes." Saitssure, Voyages dans les Alpes. Ge- 

 nev. 1787. Soliiitis, Polyhistor, cum Salmatii, 

 Exerc. Plinian. Traj. ad Khen. 1689. Stevenson, 

 in Brewster's Encyc. " Complexion" Traill, in 

 Nicholson's Journ. v. six. Vultaire, CEuvres. Par. 

 1819. Vossius, de Nili Origine. Hag. Com. 1666. 

 Voyages, Hist. Gen. des, Haye, 1747. Wafer's 

 New Voyage. Lond. 1699. Winterbottom's Account 

 of Sierra Leone. Lond. 1803. 



(J. Bostock.) 



ALBUMEN, (Fr.Allumine, Germ. Eyweis- 

 sslojf,) is one of the most important proximate 

 principles of animal bodies ; it is the leading 

 ingredient of the blood, of many of the secretions, 

 and of muscular fibre, cartilage, and membrane : 

 the white of egg (whence the generic term albu- 

 men) presents it in considerable purity, and it 

 is from this source, and from the serum of the 

 blood, that we chiefly obtain it for the purposes 

 of experiment. In this article we shall describe 

 the leading properties of albumen ; and in 

 others, refer to its principal modifications. 



The white of egg may be regarded as a 

 combination of albumen with water ; it con- 

 tains small quantities of saline substances, 

 which are inseparable in its liquid state. When 

 it is evaporated at a temperature below 120, 

 it dries into a brittle, shining, transparent sub- 

 stance of a pale yellow colour, inodorous and 

 tasteless. Its ultimate constituents, exclusive 

 of saline matters and a trace of sulphur, are 

 carbon, hydrogen, nitrogen, and oxygen ; of 

 these the relative proportions have been deter- 

 mined by Gay Lussac and Thenard, who 

 analysed the white of egg dried at 212; and 

 by Dr. Prout, who employed the dried serum 

 of slightly inflammatory blood ; the following 

 table shows its theoretical composition as con- 

 trasted with these experimental results : 



Atoms. EIIUVS. Theory. 



Carbon.. 8 48 51.61 



Hydrogen 7 7 7.53 



Nitrogen 1 14 15.05 



Oxygen 3 24 25.81 



G. Lussac. Prout. 



52.883 50.00 



7.540 7.78 



15.705 15.55 



23.872 26.67 



1 93 100.00 100.000 100.00 



White of egg, when heated to about 150, 

 coagulates, that is, it becomes a white, translu- 

 cent, and somewhat elastic substance, which, 

 when cautiously dried, shrinks up and assumes 

 the appearance of horn, becoming tough, yel- 

 lowish, and insoluble in water. Two parts of 

 white of egg and one of water entirely co- 

 agulate when duly heated ; equal parts remain, 

 under the same circumstances, semi-fluid ; a 

 mixture of one part of white of egg and ten of 

 water becomes opaque, but is not coagulated ; 

 and a milkiness is perceptible when the al- 

 bumen only forms a thousandth part of the 

 solution.* Fresh-laid eggs, and those which 

 have been oiled upon the surface do not per- 

 fectly coagulate when put into boiling water, in 

 consequence, probably, of the dilute state of 

 the albumen. One hundred parts of the fresh 

 albumen of the egg, when carefully evaporated 

 in vacuo, leave a residue = fifteen parts. One 

 hundred parts of the coagulated white of a 

 duck's egg (dried in vacuo with sulphuric 

 acid) leave 13.65 parts, which, steeped in 

 water, acquires its original appearance, but in 

 four days only took up 68 of water, though it 

 had Iost86.35.f 



When albumen is made part of the voltaic 

 circuit, it presents appearances dependent upon 

 the power used, which, when considerable, 

 excites so much heat as to coagulate it; but 

 with a feeble power and the poles sufficiently 

 distant, coagulation ensues most plentifully at 

 the negative platinum wire ; a coagulum also 

 forms at the positive wire, where acid is also 

 sparingly evolved. These phenomena are much 

 interfered with by the evolution of gaseous 

 matters at the respective poles, which occasion 

 a froth, and the appearance of more extensive 

 coagulation than actually occurs. 



When coagulated white of egg is boiled for 

 several hours, it shrinks up and becomes har- 

 dened, communicating traces of animal matter 

 to the water. Heated by high pressure steam 

 in a copper digester to 400, it blackens the 

 interior of the vessel, and dissolves, leaving 

 a small residue of unaltered albumen. The 

 solution is brown, and has the odour of boiled 

 meat (from osmazome ?). This action deserves 

 further investigation.! 



White of egg soon runs into putrefaction, 

 and evolves sulphuretted hydrogen. The se- 

 rum of blood kept for two years in a well- 

 stopped phial, blackened its interior, and be- 

 came a stinking, pale, yellow liquid, still co- 

 agulable by heat, and containing hydro-sul- 

 phate, carbonate, and acetate of ammonia, and 

 a fetid volatile matter : a portion of yellowish 

 white purulent-looking matter, containing un- 

 decomposed albumen, remained at the bottom 

 of the phial. Coagulated white of egg, even 

 under water, long resists putrefaction. 



* Bostock, Nicholson's Journal, vol. xiv. and 

 Medico-Chirurgical Transactions, vol. i. and ii. 



t Chcvrcul, |Mem. du Museum vii. 180. Ann. 

 de Ch. ct Ph. xix. 46. 



t Gmclin, Handbuch der Thcorctischcn Chcmic, 

 ii. 1053. 3rd rd. Frankfort, 1827. 



