MILK, BLOOD AND URINE 



229 



Total nitrogen . . . 

 Urea nitrogen . . . 

 Ammonia nitrogen . . 

 Uric acid nitrogen . . 

 Creatinine nitrogen . . 

 Undetermined nitrogen 



Per Cent of Total 

 Nitrogen 



87.5 per cent 



3.0 per cent 



1.1 per cent 

 3.6 per cent 

 4,9 per cent 



Hippuric Acid. — This compound, it will be recalled (p. 92), 

 is benzoyl amino-acetic acid. It is present in the urine of man 

 in about the same amount as uric acid, 0.7 grams per day. It 

 is much more abundant in herbivorous than in carnivorous 

 animals. 



Pathological Constituents, Glucose. — Two important patho- 

 logical constituents of urine should be mentioned. These are 

 glucose and albumin. Under deranged metabolic conditions, 

 the cause of which is not fully understood, the body loses its 

 power of utilizing carbohydrate food by the oxidation of glu- 

 cose. Under such conditions the glucose is excreted in the urine. 

 The pathological condition in such cases is known as glyco- 

 suria^ and the particular disease when the condition is per- 

 sistent is called diabetes mellitus. Glucose is never a constit- 

 uent of normal urine, at least in amounts detected by ordinary 

 chemical tests. Any positive test for glucose in urine is, there- 

 fore, indicative of an abnormal condition. The qualitative 

 and quantitative determination of glucose in urine is made by 

 means of Fehling's solution, or some modification of it. The 

 original Fehling's solution will not detect glucose in amounts 

 less than about o.i per cent, and the action is also interfered 

 with by creatinine, a normal constituent of urine. On this 

 account, Benedict has suggested a modification of the solu- 

 tion, which is not interfered with by creatinine and that will 

 detect as little as 0.015 per cent. The solution is made as 

 follows : 



