AMOUNT AND COMPOSITION OF THE URINE 567 



reaction of the urine, the amount of each varying with the degree of 

 the acidity of the urine (see page 558). 



On a heavy protein diet the urine is acid on account of the sulphuric 

 and other acids formed from the meat, and in this case there is a greater 

 amount of phosphoric acid and the mono-sodium hydrogen phosphate. 

 When the urine is alkaline or less acid, as it is on a vegetable diet, there 

 is a large amount of the disodium hydrogen phosphate. Since calcium 

 and magnesium phosphates are more soluble than the diphosphates of 

 the same metals, deposits of the earthy phosphates are often found in 

 neutral or alkaline urines. When the urine is heated, the diphosphate 

 of calcium breaks up into the mono-calcium and a tri-calcium phos- 

 phate, which accounts for the fine turbidity often taken for albumin in 

 the flame test. Addition of acid will cause this to disappear. The crys- 

 tals of triple phosphates which occur in alkaline urine are ammonium 

 magnesium phosphate, NH 4 MgP0 4 . 



Quantitative Changes in the Blood and Urine in Disease 



The precise diagnosis of many diseases is being greatly assisted by 

 quantitative determinations of the various nitrogenous metabolites, of 

 sugar and of inorganic salts, not only in the urine but also in the blood. 

 Although the details of this work must be sought for in the texts deal- 

 ing with clinical diagnosis, it may be of value, as indicating the practical 

 nature of the work if we give one of the tables (page 568) recently pub- 

 lished by Myers 16 which illustrates the nature of the results that have 

 been obtained. 



COMPARATIVE NITROGEN PARTITION OF URINE AND BLOOD. 

 (In per cent of total nonprotein nitrogen) 



In the foregoing table is given a comparison of the partition of the non- 

 protein nitrogenous constituents of the blood and urine as well as that of 

 the blood in nephritic conditions. A useful description of .the most prac- 

 tical and simple of the methods employed for making the necessary an- 

 alyses will be found in the papers of Myers. 



