PROTEIDS. 7 



(d.) Repeat (c.); but, before doing so, add a few drops of 

 sodic phosphate solution (10 per cent.), and note that the 

 alkaline phosphates prevent the precipitation on neutralisa- 

 tion, until at least sufficient acid is added to convert the 

 basic phosphate into acid phosphate. (See " Casein " under 

 " Milk.") 



(e.) Precipitate it by saturating its solution with crystals 

 of common salt. 



(/.) Lieberkfthn's Jelly is really a strong solution of alkali- 

 albumin. Place some undiluted white of egg in a test-tube, 

 and add, drop by drop, a strong solution of caustic potash. 

 The whole mass becomes stiff and glue-like, so that the 

 tube can be inverted without the mass falling out. 



(2.) Acid-Albumin or Syntonin. 



Preparation. (A.) To a 5 per cent, solution of egg-albu- 

 min add a few drops of dilute acid (e.g., 0*1 per cent, 

 sulphuric acid, or hydrochloric acid *2 per cent.), and warm 

 gently for several minutes = acid-albumin. 



(B.) To finely-minced muscle, free from fat, add ten 

 times its volume of dilute hydrochloric acid (4 cc. of acid in 

 1 litre of water), and allow it to stand for several hours, 

 taking care to stir it frequently ; filter, the filtrate is a solu- 

 tion of syntonin. 



(C.) Allow concentrated hydrochloric acid to act on 

 fibrin, for a time, and filter. 



Use the clear filtrate from A or B for testing. 

 (a.) The reaction is acid. 

 (6.) Boil the solution, it does not coagulate. 



(c.) Neutralise another portion with very dilute potash 

 or soda. A precipitate occurs, which is soluble in excess of 

 the alkali. Employ litmus as on previous occasions. 



(d.) Repeat (c.), but add sodic phosphate before neutralis- 

 ing ; the syntonin is precipitated as before. 



