VARIATIONS IN THE ACIDITY OF THE URINE. 293 
The results of the foregoing observations may be sum- 
med up in the following propositions : — 
1. The immediate and primary effect of a meal, whe- 
ther of purely vegetable, purely animal, or mixed 
food, was, in from one to three hours to diminish 
- the acidity of the urine; and very frequently to 
render it alkaline. The term “alkaline tide” is 
suggested to designate the period of depressed 
acidity. 
2. The remote or secondary effect of a meal was to 
uphold and increase the acidity of the urine. This 
effect of a meal was especially observed over-night 
after supper. 
3. The remote effect of animal diet appeared consi- 
derably greater than that of vegetable food. So 
that a highly animalised diet tends in the long run 
to heighten the acidity of the urine. 
4. After breakfast, the greatest depression occurred 
at the second hour; and the period of depression 
continued from two to four hours. 
5. After dinner, the greatest depression occurred at 
this is very rare. In my experience I have not found such a condition con- 
tinuing from day to day for any length of time, but rapidly passing away, 
not lasting more than some hours or a day or two; but perhaps returning 
again and again. Such urines must be carefully distinguished from ammo- 
niacal urines, which invariably indicate some disorder in the urinary pas- 
sages, generally in the bladder. 
Another cause of alkaline urine is the immersion of the body in water. 
Homolle and Duriau found that after a bath the urine always lost its acid 
reaction, even when nitric acid had been added to the bath.— Archiv. 
Génér., T. ii. 1856. 
I am also convinced that an overworked and depressed state of the system 
promotes a diminished acidity of the urine; and that a high state of health 
and yigour tends to heightened acidity. 4 
The explanation offered in the text, therefore, applies only to one particu- 
lar case of alkaline urine, and must not by any means be taken as a general 
explanation. 
