158 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



III. Preparation of Ovomucoid. 



There is present in the albumen of the hen's egg, besides 

 the ovalbumin, a mucin-like substance, in considerable 

 quantity (about one-eighth of the organic part of the dry 

 substance). This does not coagulate and is characterized 

 by its very peculiar physical conduct. 



In order to prepare it, add to the albumen of three hen's 

 eggs four times the volume of water, shake thoroughly, filter, 

 pour the filtrate into 1.5 times the volume of boiling water, 

 add acetic acid to neutral or very slightly acid reaction, 

 and heat with constant stirring over a free flame to vigorous 

 boiling. Filter, evaporate the nitrate (which should give 

 no precipitate with mercuric chloride solution) at first over 

 a free flame and then on the water-bath to about 20 cc. 

 Filter the solution again, if necessary, and pour it into 100 cc. 

 of absolute alcohol, filter, wash the precipitate once with 

 ordinary alcohol, then once with absolute alcohol, finally with 

 ether, and dry by allowing the ether to evaporate in the air. 



The ovomucoid thus obtained, which forms a fine white 

 powder, is dissolved in 100 cc. of water and the solution 

 divided into three equal parts. 



1. Evaporate one part of the solution to dryness on the 

 water-bath: a substance resembling horn is left. When 

 this is covered with water and allowed to stand it swells and 

 forms a jelly-like mass. 



2. Mercuric chloride solution gives no precipitate; but a 

 solution of tannin and also phosphotungstic acid with hydro- 

 chloric acid give precipitates. Millon's reaction is also positive. 



3. To the third part of the solution add 7 to 8 cc. of 

 hydrochloric acid, heat to boiling, keep boiling gently for five 

 minutes, let cool, neutralize and make the test for sugar 

 according to Trommer and also with the freshly mixed 

 Fehling's solution. The separation of the cuprous oxide as 

 a rule takes place only after cooling or allowing to stand. 



