ALBUMIN. 43 



drop by drop, until a slight precipitate appears, and let it stand 

 over night, when there should be a separation of the albumin in 

 rosette-like clusters of needle-shaped crystals. If the eggs are 

 not fresh a little more acid must be used enough to make a fairly 

 bulky precipitate and then the solution must stand over night in 

 a closed flask. To recrystallize, dissolve in cold water, add a few 

 drops of acetic acid, then saturated ammonium sulphate solution 

 as before till the precipitate commences to form and let it stand. 

 The yield should be about 40 per cent. 



89. Try the effect of various reagents upon the co- 

 agulation-temperature of albumin by placing about 10 

 cubic centimeters of an albumin solution in a number of 

 test-tubes, first filtering if necessary to obtain a clear 

 liquid, and adding to each three drops of the following 

 solutions (1) sodium chlorid; (2) concentrated sodium 

 chlorid and acetic acid; (3) dilute hydrochloric acid; 

 (4) sodium hydrate; (5) a solution of sodium carbonate; 

 (6) nothing. Set the test-tubes in a beaker of water and 

 heat to boiling, observing which coagulate first. It will be 

 found that acids and neutral salts favor coagulation and 

 that alkalies hinder it or prevent it altogether. 



90. Eather strongly acidify a concentrated solution 

 of albumin with hydrochloric or sulphuric acid. The albu- 

 min is precipitated. Is it coagulated? Test by diluting 

 with water. 



91. Suspend a small beaker in a larger one, keeping them 

 separate by wedges of cork; fasten by a clamp. Nearly fill both 

 with water and place in the inner one a test-tube with enough 

 solution of filtered egg albumin to stand at the same level as the 

 water. The test-tube should not touch the beaker wall. Heat 

 the water gradually, having a thermometer in the albumin solu- 

 tion. Above 45 the temperature should not be allowed to rise 

 faster than 1 per minute. Make a note of the temperature where 

 the liquid becomes opalescent and where a precipitate forms. 



