URINE 421 



that exerted by acids which have been administered. Therefore a 

 pathological increase in the output of ammonia is observed in such 

 diseases as are accompanied by an increased and imperfect protein 

 metabolism, and especially in diabetes, in which disease acetoacetic 

 acid and /3-hydroxy butyric acid are found in the urine in combination 

 with the ammonia. 



Folin claims that a pronounced decrease in the extent of protein 

 metabolism, as measured by the total nitrogen in the urine, is frequently 

 accompanied by a decreased elimination of ammonia. The ammonia 

 elimination is therefore probably determined by other factors than the 

 total protein catabolism as such. Furthermore, he believes that a 

 decided decrease in the total nitrogen excretion is always accompanied 

 by a relative increase in the ammonia-nitrogen, provided the food is of a 

 character yielding an alkaline ash. 



The quantitative determination of ammonia must be made upon 

 the fresh urine, since upon standing the normal urine will undergo am- 

 moniacal fermentation (see page 379). 



EXPERIMENTS 

 (See Experiment 2 under Phosphates, page 426.) 



Sulphates 



Sulphur in combination is excreted in two forms in the urine: first, 

 as unoxidized, loosely combined or neutral sulphur, and second, as oxidized 

 or acid sulphur. The unoxidized or neutral sulphur is excreted mainly 

 as a constituent of such bodies as cystine, cysteine, taurine, hydrogen 

 sulphide, ethyl sulphide, thiocyanates, sulphonic acids, oxyproteic acid, 

 alloxyproteic acid, and uroferric acid. The amount of neutral sulphur 

 eliminated is in great measure independent of the extent of protein 

 decomposition or of the total sulphur excretion. In this characteristic 

 it is somewhat similar to the excretion of creatinine. The oxidized 

 sulphur is eliminated in the form of sulphuric acid, principally as salts of 

 sodium, potassium, calcium, and magnesium; a relatively small amount 

 occurs in the form of ethereal sulphuric acid, i.e. t sulphuric acid in com- 

 bination with such aromatic bodies as phenol, indole, skatole, cresol, 

 pyrocatechol, and hydroquinol. Sulphuric acid in combination with 

 Na, K, Ca or Mg is sometimes termed inorganic or preformed sulphuric 

 acid, whereas the ethereal sulphuric acid is sometimes called conjugate 

 sulphuric acid. The greater part of the sulphur is eliminated in the 

 oxidized form, but the absolute percentage of sulphur excreted as the 



