180 PHYSIOLOGICAL CHEMISTRY. 



10. Caseinogen. Extract the fresh feces first with a dilute so- 

 lution of sodium chloride, and later with water acidified with dilute 

 acetic acid r to remove soluble proteins. Now extract the feces with 

 0.5 per cent sodium carbonate and filter. Add dilute acetic acid 

 to the filtrate to precipitate the caseinogen, being careful not to add 

 an excess of the reagent as the caseinogen would dissolve. Filter 

 off the caseinogen and test it according to directions given on page 

 224. Caseinogen is found principally in the feces of children who 

 have been fed a milk diet. Mucin would also be extracted by the 

 dilute alkali, if present in the feces. What test could you make on 

 the newly precipitated body to differentiate between mucin and 

 caseinogen ? 



11. Nucleoprotein. Mix the stool thoroughly with water, trans- 

 fer to a flask, and add an equal amount of saturated lime water. 

 Shake frequently for a few hours, filter, and precipitate the nucleo- 

 protein with acetic acid. Filter off this precipitate and test it as 

 follows : 



(a) Phosphorus. Test for phosphorus by fusion (see page 251). 



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



(c) Protein Color Test. Try any of the protein color tests. 

 What proof have you that the above body was not mucin? 



What other test can you use to differentiate between nucleoprotein 

 and mucin? 



12. Albumin and Globulin. Extract the fresh feces with a 

 dilute solution of sodium chloride. (The preliminary extract from 

 the preparation of caseinogen (10), above, may be utilized here.) 

 Filter, and saturate a portion of the filtrate with sodium chloride 

 in substance. A precipitate signifies globulin. Filter off the pre- 

 cipitate and acidify the filtrate slightly with dilute acetic acid. A 

 precipitate at this point signifies albumin. Make a protein color 

 test on each of these bodies. 



13. Proteose and Peptone. Heat to boiling the portion of the 

 sodium chloride extract not used in the last experiment. Filter off 

 the coagulum, if any forms. Acidify the filtrate slightly with 

 acetic acid and saturate with sodium chloride in substance. A pre- 

 cipitate here indicates proteose. Filter it off and test it according 

 to directions given on page 115. Test the filtrate for peptone by 

 the biuret test. 



14. Inorganic Constituents. Prepare a dilute aqueous solution 

 of dry feces and decolorize it by means of purified animal charcoal. 

 Make the following tests upon the clear solution : 



