572 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



B. The Bence-Jones Protein. 



In rare cases of disease of the bone-marrow, a peculiar protein, the 

 Bence-Jones protein, appears in the urine. 



This protein is precipitated on heating the urine to 50-60 and redis- 

 solves, more or less completely, according to the reaction and the amount of 

 salt in the urine, when the heating is continued to the boiling-point. The 

 protein is not dialysable and can be precipitated by adding double the 

 volume of saturated ammonium sulphate solution or alcohol. The exact 

 nature of the body is unknown but it has resemblances to globulin and pro- 

 teose and yields the same amino acids on hydrolysis. 



(3) BLOOD. 



The appearance of the urine may be reddish. The urine is centrifuged 

 to separate corpuscles and these are examined with the microscope. 



The guaiac reaction (p. 476) may be tried and the solution is examined 

 with the spectroscope. 



Hsemochromogen is prepared by boiling with caustic soda, cooling and 

 reducing with ammonium sulphide ; this pigment shows the absorption bands 

 when the other blood pigments do not (see under haemoglobin). 



The pigment can be precipitated with the earthy phosphates by caustic 

 soda. 



(4) BILE. 



Bile pigments are tested for as follows : 



The urine is filtered through paper and Gmelin'sl 



f bee under 



reaction is performed. , ., 



Huppert's reaction is convenient for small quantities. I 



If some tincture of iodine be poured carefully upon some urine in a test 

 tube, a green ring appears at the junction of the liquids. 



Bile acids are tested for by 



(1) Pettenkofer's test (after concentration if necessary).! ^ , 



(2) Hay's test. 



(3) Oliver's test. [ blle ' 



