168 ESSENTIALS OF CHEMICAL PHYSIOLOGY 



and so the urine for clinical purposes may be considered free from sugar. 

 This reduction of picric acid by normal urine is due to creatininr. 



6. Test for Acetone. Acetone is often found in diabetic urine. Add to the 

 urine a dilute solution of sodium nitro-prusside and a little 20-per-cent. 

 caustic potash. A red colour is produced. Acidify with strong acetic 

 acid. The colour disappears at once in the absence of acetone, but re- 

 mains or is intensified in its presence. 



The full significance and causes of pathological urine cannot be 

 appreciated until a theoretical and practical acquaintance with disease 

 is obtained, and we shall briefly consider only those abnormal con- 

 stituents which are most frequently met with. 



PROTEINS IN THE URINE 



There is no protein matter in normal urine, and the most common 

 cause of the appearance of albumin in the urine is disease of the 

 kidney (Bright's disease). The best methods of testing for and esti- 

 mating the albumin are given in the practical heading to this lesson. 

 The term ' albumin ' is the one used by clinical observers. Properly 

 speaking, it is a mixture of serum albumin and serum globulin. 



A condition called ' peptonuria,' or peptone in the urine, is ob- 

 served in certain pathological states, especially in diseases where 

 there is a formation of pus, and particularly if the pus is decomposing 

 owing to the action of a bacterial growth called staphylococcus ; one 

 of the products of disintegration of pus cells appears to be peptone ; 

 and this leaves the body by the urine. The term ' peptone,' however, 

 is in the strict sense incorrect ; the protein present is deutero- 

 proteose. In the disease called ' osteomalacia ' a proteose is usually 

 found in the urine, which more nearly resembles hetero-proteose in 

 its characters. 



SUGAR IN THE URINE 



Normal urine contains no sugar, or so little that for clinical pur- 

 poses it may be considered absent. It occurs in the disease called 

 diabetes mellitus, which can be artificially produced by the methods 

 described on pp. 87, 88. 



The methods usually adopted for detecting and estimating the 

 sugar are given at the head of this lesson. The sugar present is 

 dextrose. Lactose may occur in the urine of nursing mothers. 

 Diabetic urine also contains hydroxybutyric acid, and may contain 

 or yield on distillation acetone and ethyl -diacetic acid. 



Fehling's test is not absolutely trustworthy. Often a normal urine will 

 decolorise Fehling's solution, though seldom a red precipitate is formed. 

 This is due to excess of urates and creatinine. Another substance, called 



