UREA. 681 



Thus LONG and GEPHART found in the urine of six healthy men to whom 

 the same qualitative diet was fed for a long time, the following division 

 of the nitrogen in percentage of the total nitrogen: urea 79.87-84.34, 

 creatinine 5.21-6.87, ammonia 3.6-4.74, uric acid 1.57-1.99, purine 

 0.33-0.96 and rest nitrogen 4.23-6.01 per cent. SJOQVIST has made 

 similar determinations on new-born babes from 1 to 7 days old. From 

 all these analyses we obtain the following figures (A for adults and B for 

 new-born babes). Of the total nitrogen there exists: 



A. B. 



Per Cent. Per Cent. 



Urea 84-91 73-76 



Ammonia 2-5 7.8-9.6 



Uric acid 1-3 3.0-8.5 



Remaining nitrogenous substances 7-12 7 . 3-14 . 7 



The variable relation between uric acid, ammonia, and urea nitro- 

 gen in children and adults is remarkable, since the urine of children 

 is considerably richer in uric acid and ammonia, and considerably poorer 

 in urea, than the urine of adults. A much larger number of analyses 

 of children's urine is necessary to explain the division of the nitrogen 

 therein. The absolute quantity of urea nitrogen in adults amounts to 

 about 10-16 grams per day. In disease the proportion of the nitroge- 

 nous substances may be markedly changed, and a decrease in the quan- 

 tity of urea and an increase in the quantity of ammonia have been observed 

 in certain diseases of the liver. This will be considered in detail in 

 connection with the formation of urea in the liver. It is natural that 

 there should be a diminished formation of urea after a decrease in the 

 ingestion of proteins or in a lowered catabolism. In diseases of the 

 kidneys which disturb or destroy the integrity of the epithelium of 

 the convoluted urinary tubules, the elimination of urea is considerably 

 diminished. 



Recently by means of PFAUNDLER'S * method, by precipitating the urine with 

 phosphotungstic acid and closely studying the precipitate as well as the filtrate, 

 it has been possible to learn further about the division of the nitrogen of the urine. 

 We determine a, the total nitrogen; b, the nitrogen of the phosphotungstate pre- 

 cipitate; and c, the nitrogen in the filtrate from the phosphotungstate pre- 

 cipitate. This last contains the urea, hippuric acid, oxyproteic acids, and other 

 bodies whose nitrogen is ordinarily designated as monaminp-acid nitrogen. The 

 urea nitrogen is especially determined. The bodies precipitated by phospho- 

 tungstic acid are not all known; but uric acid and purine bases, ammonia, 

 creatinine, pigments, diamino-acids, diamines and ptomaines (if they occur), sul- 

 phocyanides, carbamic acid, urine mucoid, and proteid belong to this group. 

 Special methods have been suggested for the determination of several of these 

 substances (see below). 



The urea nitrogen is always the greatest part of the total nitrogen, 

 but otherwise the division of the nitrogen undergoes considerable varia- 



1 Zeitschr. f. physiol. Chem., 30. 



