44 THE PHOTEINS. 



92. Put some of the clear albumin solution into three test- 

 tubes. Make one of them faintly acid by a drop of very dilute 

 hydrochloric acid; add to the second enough of a very dilute solu- 

 tion of sodium carbonate to make it faintly alkaline; have the 

 third exactly neutral. Heat them as in the last experiment, ob- 

 serving the coagulation temperature by means of a sensitive ther- 

 mometer. Report results. 



93. Test the solubility in cold water of some egg- 

 albumin which has been dried at a low temperature. It 

 dissolves slowly, showing that coagulation has not occurred. 

 The solution will give the albumin reactions. 



94. Place some of this thoroughly dry egg-albumin 

 in a dry test-tube and let this stand for several minutes 

 in a beaker of boiling water. After removal it will dis- 

 solve in cold water as before. Coagulation has not taken 

 place, since for this the presence of water is necessary. 



95. Test solutions of serum-albumin and egg-albu- 

 min with an excess of nitric acid without heat and also by 

 warming, and notice that the serum-albumin is more 

 easily soluble. Try the same with concentrated hydro- 

 chloric acid. 



96. Show that a solution of egg-albumin forms an 

 insoluble compound when added to solutions of mercury, 

 silver, or copper. 



GLOBULINS. 



The globulins are distinguished from all the other 

 albuminous substances by being soluble in dilute salt solu- 

 tions, but insoluble in water. From this solution they are 

 precipitated by diluting freely with water or by removing 

 the salt by diatysis. They can, in this manner, be sepa- 

 rated from the albumins which remain in solution. The 

 globulins are, as a rule, precipitated by saturating the 



