THE URINE. 347 



necessary for the determination of urea, and also for instructions in 

 the use of this instrument, we must refer the reader to the direc- 

 tions accompanying the apparatus. For pure urea solutions Es- 

 BACH'S apparatus gives quite exact results. The determination of 

 urea in urine by this method always gives results somewhat too 

 low, and as a rule a result is obtained which on an average is about 

 0.1$ lower than that obtained with LIEBIG'S titration method. 



Creatinin, C 4 H,N 3 0, or NH : tX^oiijIjH,' * s generally con- 



sidered as the anhydride of creatin (see page 257) found in the 

 muscles. It occurs in human urine and in that of certain mam- 

 malia. It has also been found in ox-blood (VoiT), milk, though in 

 very small amounts (WEYL), and in the flesh of certain fishes. 



The quantity of creatinin in human urine is for a grown man, 

 voiding a normal quantity of urine in the 24 hours, 0.6-1.3 grms. 

 (NEUBAUER), or on an average 1 grm. The quantity is dependent 

 on the food, and decreases in starvation. Sucklings do not gener- 

 ally eliminate any creatinin, and it only appears in the urine when 

 the milk is replaced by other food. The quantity of creatinin in 

 urine varies as a rule with the quantity of urea, although it- is in- 

 creased, more by flesh (because the flesh contains creatin) than by 

 albumin. GROCCO claims that the elimination of creatinin is in- 

 creased by muscular activity, which is contrary to the statements 

 of HOFMANN and others. The behavior of % creatinin in disease is 

 little known. By increased exchange of material the amount is 

 increased, while by decreased exchange of material, as in anaemia 

 and cachexia, it is diminished. 



Creatinin crystallizes in colorless, shining monoclinic prisms 

 which differ from creatin crystals in not becoming white with loss 

 of water when heated to 100 C. It dissolves in 11.5 parts cold 

 water, but more easily in warm water. It requires nearly 100 parts 



rubber nipple, a cubic centimetre of the urine to be tested, which should be 

 taken from the total excretion of the twenty four hours, the exact quantity of 

 which should be noted. The end of the pipette is passed into the bulb until the 

 point is exactly under the vertical tube, and slowly compress the nipple. The 

 urine being lighter than the hypobromile solution rises through it, and on its 

 way the contained urea is decomposed and its nitrogen set free. The quantity 

 of urea contained in the one cubic centimetre of urine used is rend off on the 

 instrument. TRANSLATOR. 



