86 REPORTS ON THE STATE OF SCIENCE.—1917. °* 
White of egg contains 10 to 12 per cent. of albumin, about 88 per cent. 
of water, rather less than 1 per cent. of mineral matter, and also about 
1 per cent. of a carbohydrate. In dealing with white of egg, usually 
the hen’s egg is implied. There are differences in the properties of the 
whites of eggs from different birds. For instance, the white of the duck 
egg has a bluish-cast and on heating coagulates to a stiffer gel. 
Egg white consists of a glairy liquid portion and a glutinous portion ; 
the latter, equal to about one-fifth of the whole, does not mix with the 
former but can be separated by means of a sieve. In what respect these 
two portions differ from one another we do not know, but there is certainly 
a difference in their alkalinity, the alkalinity of the glutinous portion 
being = to 0-473 per cent. of NaHO, and the more fluid portion, alkalinity 
= 0-585 per cent. NaHO. White of egg when fresh shows a distinct 
alkalinity to phenol-phthalein, showing the presence of HO ions, this being 
= to 0-026 to 0-159 per cent. NaHO ; after keeping for a time, which may 
vary according to the quality of the egg, this reaction is not observed. 
The white is, however, always alkaline to methyl orange = to about 0-5 
per cent. of NaHO. Addition of alkali to albumin results in a considerable 
increase in viscosity; with 20 c.c. white of egg and 3 c.c. N.NaHO the 
mixture sets to a solid gel after standing for a few hours; on further 
addition of alkali the albumin again becomes liquid, forming a thin fluid 
(alkali-albumin). Acids reduce the viscosity and finally coagulate the 
albumin, or, in solution, cause a flocculent precipitate. (For the effect 
of electrolytes on the viscosity, coagulation, and osmotic pressure of albumin 
see ‘ Colloids and their Viscosity,’ Faraday Soc., March 12, 1913.) Acids, 
especially mineral acids, readily coagulate albumin; potassium ferro- 
cyanide in acid solution is a powerful coagulant, being used as a test for 
traces of albumin. It is also coagulated by phenol, cresol, tannic acid, 
and by formaldehyde. It gradually yields a precipitate when shaken 
with ether or turpentine. 
Egg white is purified for use in painting by adding dilute acetic acid 
till neutral and straining ; this removes the glutinous portion and renders 
the material much more fluid. The painting can be rendered insoluble 
either by heat or by tannic acid (A. H. Church, ‘ Chemistry of Paints and 
Painting,’ p. 65). 
Dialysed albumin yields a clear gel with acetic acid; on heating, the 
mixture forms a clear fluid which gelatinises again on cooling. The 
viscosity of sols of albumin and acetic acid increases by keeping up to 
18 to 20 days; the viscosity of albumen is also increased by addition of 
acetic acid up to 7-01 per cent. ; further addition decreases the viscosity 
up to 11-22 per cent., when there is again a rise, Salts cause a rise in the 
rapidity of the reaction but not in the intensity (L. Zoja, ‘ Zeitschr. Chem. 
Ind. Kolloide,’ 1908, 3, 249, 269). 
Albumin is readily salted out, salts of alkaline earths acting in this 
respect more powerfully than the alkalies, salts of zinc aluminium, and the 
heavy metals powerfully coagulate albumin. 
Slaked lime and white of egg set to a solid; this mixture has been used 
as a cement for a very long time (D. C. Séuef (J. Schuberth), Eng. Pat. 
1,225, 1862). A mixture of blood and-slaked lime is a variant. White 
of egg in contact with iron or iron rust adsorbs Fe,(HO),, becoming blood- 
red in colour (iron albuminate), at the same time losing its viscosity. 
Albumin in solution is coagulated at temperatures above 54°; at that 
