224 PHYSIOLOGICAL CHEMISTRY. 



the papers and allow the ether to evaporate spontaneously. Grind 

 the precipitate to a powder in a mortar. Upon the caseinogen pre- 

 pared in this way make the following tests : 



(a) Solubility. Try the solubility in the ordinary solvents. 



(&) Millon's Reaction. Make the test according to the direc- 

 tions given on page go. 



(c) Biuret Test. Make the test according to directions given on 

 page 92. 



(d) Hopkins-Cole Reaction. Make the test according to the di- 

 rections given on page 101. 



(e) Loosely Combined Sulphur. Test for loosely combined sul- 

 phur according to the directions given on page 102. 



(/) Fusion Test for Phosphorus. Test for phosphorus by fusion 

 according to directions given on page 251. 



14. Coagulable Proteins of Milk. Place the filtrate from the 

 original caseinogen precipitate in a casserole and heat, on a wire 

 gauze, over a free flame. As the solution concentrates, a coagulum 

 consisting of lactalbumin and lacto globulin will form. Continue 

 to concentrate the solution until the volume is about one-half that 

 of the original solution. Filter off the coagulable proteins (re- 

 serve the filtrate) and test them as follows: 



(a) Millon's Reaction. Make the test according to the direc- 

 tions given on page 90. 



(b) Biuret Test Make the test according to the directions given 

 on page 92. 



(c) Hopkins-Cole Reaction. Make the test according to the di- 

 rections given on page 101. 



15. Detection of Calcium Phosphate. Evaporate the filtrate 



from the coagulable proteins, on a water- 

 bath, until crystals begin to form. It may 



be necessary to concentrate to 15 c.c. before 

 any crystallization will be observed. Cool 

 the solution, filter off the crystals (reserve 

 the filtrate) and test them as follows: 



(a) Microscopical Examination. Exam- 

 j ne * e "y 5 ^^ & compare them with those 

 in Fig. 76. 



(6) Dissolve the crystals in nitric acid. Test part of the acid 

 solution for phosphates. Render the remainder of the solution 

 slightly alkaline with ammonia, then acidify with acetic acid and 

 add ammonium oxalate. Examine the crystals under the micro- 

 scope and compare them with those in Fig. 99, p. 345. 



