THE ALBUMIN ATES. 47 



ALKALI ALBUMIN. 



107. Prepare from a solution of albumin by warm- 

 ing with alkali, like sodium hydrate. 



108. The solid alkali albumin can be obtained by adding 

 strong sodium hydrate, drop by drop, to the white of an egg, 

 stirring continually. No more must be added after it has become 

 gelatinous, as it will then dissolve. Wash the solid in cold water, 

 in which it is insoluble, though it is soluble without difficulty in 

 warm water. (It is known as Lieberkiihn's jelly.) 



109. Observe that the alkali albumin is soluble in 

 dilute acids or alkalies. If the conversion is incomplete 

 complete solution does not occur. An excess of acid may 

 precipitate it. 



110. Dissolve some of the solid substance in hot 

 water or use the solution obtained from Experiment 107. 

 Add a few drops of phenolphthalein, which gives a red 

 color, showing that the solution is alkaline. Add slowly 

 dilute acid until the red color has just disappeared, when 

 the solution will be neutral. The alkali albumin is pre- 

 cipitated. If, now, more acid is added, the precipitate dis- 

 solves. It is, consequently, like the acid albumin, precipi- 

 tated by neutralizing. 



111. Show that dissolved alkali albumin, like acid 

 albumin, is not coagulated by boiling. 



112. Show there is a cleavage of egg-albumin during 

 the formation of alkali albumin with a splitting off of the 

 loosely combined (cystin) sulphur. 



First heat the albumin solution with sodium hydrate 

 for several minutes. The sulphur which has been split off 

 from the albumin molecule remains in the solution as so- 

 dium sulphid and does not discolor a piece of filter paper 



