GENERAL CHARACTERISTICS OF THE URINE. 229 



of albumins and alkaline salts present, or of salts which can be trans- 

 formed within the body into alkaline carbonates, it follows that a 

 highly acid urine must also result when an increased destruction of 

 tissue-albumins is taking place from whatever cause. We accord- 

 ingly find a very acid urine in various pathological conditions, nota- 

 bly in fevers. 



An alkaline urine will similarly result when, as in pneumonia and 

 in diseases in which large accumulations of fluid occur in the 

 serous cavities of the body, and where a certain amount of alka- 

 line salts has thus been withdrawn from the circulation, absorption 

 subsequently occurs. Alkaline salts are, however, retained from 

 the ingested food, and an increased elimination occurs when the addi- 

 tional supply finds its way into the plasma from these various sources. 

 A notable change in the normal alkalinity of the blood can hence 

 scarcely occur so long as a sufficient amount of alkali is furnished in 

 the food. 



In order to decide whether the alkaline reaction of a specimen of 

 urine is due to the presence of fixed or volatile alkali, a strip of red 

 litmus-paper is clamped in the cork of the bottle, and so arranged as 

 not to touch the liquid. If free ammonia is present, the red color 

 changes to blue, while fixed alkali is indicated only when the paper 

 comes into contact with the urine. 



Determination of the Acidity of the Urine. The total acidity 

 which indicates the acidity due to diacid phosphates and free 

 organic acids is first obtained as follows : 25 c.c. of urine are 

 treated with 1, or at most 2 drops of an 0.5 per cent, alcoholic solu- 

 tion of phenolphthalein and 15-20 grammes of powdered potassium 

 oxalate. The solution is shaken for a minute and titrated at 

 once with decinormal sodium hydrate solution until a faint, yet 

 distinct pink color, is obtained. The flask should be shaken during 

 the titration so as to keep the solution as strong as possible in oxa- 

 late. The acidity is expressed in terms of decinormal sodium 

 hydrate solution, for the total amount of urine of twenty-four 

 hours. The total acidity is termed T. 



In a second specimen the total phosphates are then determined 

 P. (see p. 233). The result is expressed in terms of decinormal 

 acid, viz., alkali as above (1 c.c. T n g- = 7.1 milligrammes of P 2 O 5 ). 

 T.-P. then indicates the acidity due to uncombined organic acids 

 (O. A.), and the difference the mineral acidity (M. A.) 



It may happen that the acidity calculated from the total phos- 

 phates is greater than the titrated acidity ; in that case practically 

 no free organic acids are present and the titrated acidity represents 

 the amount of phosphates present in the diacid form. Urines of 

 this kind are turbid, unless they are also free from calcium 

 (Folin). 



As average normal value for the acidities of the total bulk of the 

 twenty-four-hour urine Folin obtained 617 (c.c y 1 ^ n. acid, viz., 

 alkali), of which 304 was referable to mineral and 313 to organic 



