32O PHYSIOLOGICAL CHEMISTRY. 



3. v. Aider's Method. Acidify 10 c.c. of urine with hydro- 

 chloric acid, add phosphotungstic acid until no more precipitate 

 forms and centifugate 1 the solution. Decant the supernatant fluid, 

 add some absolute alcohol to the precipitate and centrifugate again. 

 This washing with alcohol is intended to remove the urobilin and 

 hence should be continued so long as the alcohol exhibits any colora- 

 tion whatever. Now suspend the precipitate in water and add 

 potassium hydroxide to bring it into solution. At this point the 

 solution may be blue in color, in which case decolorization may be 

 secured by gently heating. Apply the biuret test to the cool solu- 

 tion. A positive biuret test indicates the presence of proteoses. 



4. Detection of " Bence-Jones' Protein." Heat the suspected 

 urine very gently, carefully noting the temperature. At as low a 

 temperature as 40 C. a turbidity may be observed and as the tem- 

 perature is raised to about 60 C. a flocculent precipitate forms and 

 clings to the sides of the test-tube. If the urine is now acidified 

 very slightly with acetic acid and the temperature further raised to 

 1 00 C. the precipitate at least partly disappears; it will return upon 

 cooling the tube. 



This property of precipitating at so low a temperature and of 

 dissolving at a higher temperature is typical of " Bence-Jones' pro- 

 tein " and may be used to differentiate it from all other forms of 

 protein material occurring in the urine. 



NUCLEOPROTEIN. 



There has been considerable controversy as to the proper classi- 

 fication for the protein body which forms the " nubecula " of 

 normal urine. By different investigators it has been called mucin, 

 mucoid, phospho protein, nucleoalbumin and nudeo protein. Of 

 course, according to the modern acceptation of the meanings of 

 these terms they cannot be synonymous. Mucin and mucoid are gly- 

 coproteins and hence contain no phosphorus (see p. 106), whereas 

 phosphoproteins and nucleoproteins are phosphorized bodies. It 

 may possibly be that both these forms of protein, i. e., the glycopro- 

 tein and the phosphorized type, occur in the urine under certain con- 

 ditions (see page 290). In this connection we will use the term 

 niideoprotein. The pathological conditions under which the con- 

 tent of nucleoprotein is increased includes all affections of the 

 urinary passages and in particular pyelitis, nephritis and inflamma- 

 tion of the bladder. 



1 If not convenient to use a centrifuge the precipitate may be filtered off and 

 washed on the filter paper with alcohol. 



