82 



CHEMICAL PHYSIOLOGY. 



The acidity is increased during the resolution of febrile diseases; 

 is excessive in gout and acute rheumatism, and whenever much 

 uric acid is given off (uric acid diathesis); in saccharine diabetes, 

 when certain acids are taken with the food (CO 2 , benzoic). 



The amount of the acidity may be determined by using a 

 standard solution of caustic soda. 



10. Fermentation of the Urine. When urine is freely exposed 

 to the air it undergoes two fermentations (1) the add; (2) the 

 alkaline. The urine at first becomes slightly more acid, from the 

 formation of lactic and acetic acids (although this is denied by 

 some observers), then it gradually becomes tieutral, and finally 

 alkaliiie from putrefaction. It becomes lighter in colour, turbid, 

 and a whitish heavy precipitate occurs ; a pellicle forms on the 

 surface, it swarms with bacteria, and it has an ammoniacal odour, 

 which is due to the splitting up of the urea, thus 



CON 2 H 4 + 2H 2 = (NH 4 ) 2 C0 3 



The carbonate of ammonia makes the urine alkaline, and the 

 earthy phosphates are precipitated because they are insoluble in 



an alkaline urine. 

 The phosphate of 

 lime is precipitated 

 as such, while the 

 phosphate of mag- 

 nesia unites with 

 the ammonia and is 

 precipitated as am- 



j I rtr\ i- ^ * JT ~'-v_ ^ ~ F^ 1 -w ff? (Qxs 4*^. 1 



Fig. 16. Deposit in "acid fermentation" of 

 urine. a. Fungus ; b, amorphous sodium urate ; 

 c, uric acid ; d, calcium oxalate. 



urine may be kept " sweet 



phosphate or triple 

 phosphate (Mg 

 NH 4 P0 4 + 6H 2 0). 

 It is not known 

 what ferment 

 causes this reaction 

 whether mucus, 

 bacteria-like or- 

 ganisms, or some 

 amorphous fer- 

 ment. 



N.B. Although 

 for a long time in perfectly clean 



