110 THE CHEMICAL COMPOSITION OF THE BODY 



ALBUMINS AND GLOBULINS. 



5. Properties of Albumins and Globulins. Try out the solubility 

 and the precipitation tests indicated in the following table for a solution of 

 ovalbumin, and on edestin furnished by the instructor. 



ALBUMINOIDS. 



6. Keratin. Horn shavings are most conveniently used for the experi- 

 ments with keratin. 



a. Try the solubility of keratin in water, 10 per cent, salt solution, dilute 

 hydrochloric acid, and dilute potassium or sodium hydroxide. 



b. Make a test for loosely combined sulphur as in experiment 2, d, 

 page 1 06. 



c. Try Milieu's reaction and the biuret reaction. 



d. Try the solubility of keratin in the artificial gastric and pancreatte 

 juice furnished by the instructor. 



7. Collagen. The tendo achillis of the ox may be used for the prepara- 

 tion of collagen. 



a. Clean the tendon and cut it into small pieces. Wash the pieces in 

 dilute salt solution in order to remove the soluble protein, and then w r ash 

 with distilled water. Transfer the pieces of washed tendon to a flask and 

 add 100 c.c. of saturated lime-water and same amount of distilled water. 

 The flask should be shaken at intervals for twenty-four hours. The lime- 

 water dissolves the mucoid in the tendon. Filter off the pieces of tendon 

 and save the filtrate for a later experiment. The residue of the tendon con- 

 sists of the albuminoid collagen and a little elastin. We may consider the 

 tests to follow as being made upon collagen. 



b. Cut the collagen into very fine pieces and try the solubility as in 6 a 

 above. 



* If not precipitated, acidify and note result. 



t See page 89. 



% On standing under alcohol. 



