220 ALBUMEN. 



561. Dry albumen may be kept for a long time 

 without undergoing decomposition ; but in solution, 

 or when moist, it is very liable to change. When 

 heated, it burns ; and the results of its decay, as 

 well as of its combustion, are water, carbonic acid, 

 and ammonia ; it leaves a small quantity of white 

 ash, which consists principally of phosphate of lime. 



562. When perfectly pure, albumen appears to be 

 nearly insoluble in pure water ; but it readily dis- 

 solves in a weak alkaline solution, a very small quan- 

 tity of which, gives water the power of dissolving 

 albumen. Albumen is also soluble in acetic and 

 phosphoric acid ; these substances, therefore, do not 

 throw it down from its alkaline solutions, but it is 

 precipitated by sulphuric, muriatic, and most other 

 acids, and the albumen thus thrown down is found to 

 have combined with a portion of the acid used to 

 precipitate it. 



563. Most metallic salts also precipitate solutions 

 of albumen, forming with it insoluble compounds ; 

 it is for this reason, that white of egg is recommended 

 in certain cases of poisoning, as, for example, with 

 corrosive sublimate. Albumen is used in many cases 

 as a fining material; when mixed with any solution 

 which it is desired to purify, and then precipitated, it 

 separates in a curdy form, and, in so doing, entangles 

 and separates the solid impurities previously suspend- 

 ed in the solution. When there is a large quantity 

 of free alkali, or of acetic acid present, a solution of 

 albumen cannot be coagulated by heat alone. 



