PHYSIOLOGICAL CHEMISTRY 415 



half-an-hour with diastase (2 grm.) and taken with 300 c.c. cream. 

 It contained only about 1 grm. of nitrogen and could be taken without 

 great discomfort to the person for several days. It might have been 

 better had it contained twice as much cream, for then the breakdown of 

 tissue protein which occurred would have been diminished. 



Nitrogen rich diet. Nitrogen poor diet. 



Volume of urine - 1170 c.c. 385 c.c. 



Total nitrogen - - 16 '8 grm. 3 '60 grm. 



Urea-nitrogen - - 14'7 grm. =87 '5% of total N. 2 "20 grm. =617% of total N. 



Ammonia nitrogen - 0'49grm. = 3*0% ,, 0'42grm. = 11'3% ,, 



Uric acid nitrogen - O'lSgrm. = M% 0'09grm.= 2-5% 



Creatinin nitrogen - O'oSgrm. = 3'6% ,, O'GOgrm. =17*2% 



Undetermined nitrogen 0'85 grm. = 4'9% ,, 0'27grm. = 7'3% 



When the intake of nitrogen by the diet is much reduced, the 

 percentage of the total nitrogen excreted as urea markedly falls, whilst 

 that of the other nitrogenous bodies rises. It will further be noted, 

 however, that the absolute amounts of all these bodies falls, except in 

 the case of creatinin, which remains unchanged. 



The total sulphate excretion is made up of inorganic sulphates, 

 ethereal sulphates, and neutral sulphur, and the relative amounts of 

 these excreted on a rich and a poor diet show striking resemblances to 

 the nitrogenous bodies, as will be discussed later. 



CHAPTER XVII. 

 UREA. 



UREA is the diamide of carbonic acid. 



Carbonic acid. Urea. 



m /OH ro^ NH 2 



CO <OH. CO <NH 2 . 



In common with other acid amides, urea has weak basic properties, 

 forming unstable salts with nitric and oxalic acids. 



EXPERIMENT I. To some urine, which has been evaporated to 

 small bulk on a water-bath, add some pure, colourless (not fuming) 



