EGGS OF FOWLS. 447 



It is stated by Berzelius, I know not on what authority, to be 

 easily converted into gelatin when boiled in water. 



3. The glairy liquid called the white coagulates into a firm 

 white solid when heated to 159. Hence it is a solution of al- 

 bumen in water. This aqueous solution when evaporated to 

 dryness leaves about 14 per cent of albumen. Dr Bostock has 

 shown that it contains also a little mucus. According to him the 

 mean constitution of white of egg is, 



Water, 80 



Albumen, . 15*5 

 Mucus, . 4 '5 



100* 



Dr Prout determined by combustion the'quantity of fixed con- 

 stituents which albumen contains. If we suppose the original 

 weight of the egg to have been 1 000 grains, the following table 

 shows the weight of the fixed constituents in three different eggs : 



No. 1. No. 2. No. 3. 



Grains. 



Sulphuric acid, . . 0-29 0-15 0-18 



Phosphoric acid, . . . 0-45 0-46 0-48 



Chlorine, . . . 0-94 0.93 0-87 



Potash, soda, and carbonates of do. 2-92 2-93 2-72 



Lime, magnesia, and carbonates of do. 0-30 0-25 0*32 



4-90 4-72 4-57 



It was long uncertain whether the sulphur and phosphorus 

 exist in the white of egg in the state of sulphuric and phos- 

 phoric acids, or in that of sulphur and phosphorus. What 

 renders the second of these suppositions probable is, that 

 the acids are too small in quantity to neutralize the bases ; and 

 it is well-known that the white of egg has an alkaline reaction. 

 The existence of these bodies in the state of sulphur and phos- 

 phorus has been at last proved by M. Mulder, as has been no- 

 ticed when treating of albumen in a preceding chapter of this 

 volume* 



4. The yolk consists of water, albumen, and fixed oil, mixed 

 so as to constitute an emulsion. It contains also a colouring mat- 

 ter, for which it is indebted for its yellow colour. Dr Prout ana- 



* Nicholson's Jour. xi. 246, and xiv. 142. 



