VARIATIONS IN THE ACIDITY OF THE URINE. 277 
TABLE XX. shows the mean amount of Uric Acid separated 
on the seven days composing Table [11—during the alkaline 
tide after dinner ; from nine to eleven p.m.; and during the 
night. 
Uric acid Uric acid Uric acid 
Time per 1000 grains per 100 grains 
of liquid urine perbour of solid urine 
4-7 p.m., alkaline tide 0-40 0°36 0-83 
9-11 p.m., acidity restored 0-18 0-13 0°34 
1-7 a.m., urine of sleep 0°39 0-10 0-60 
The urine of the alkaline tide was, therefore, rich in 
uric acid (as calculated per 1000), rather more so even 
than the night urine, which in nearly every instance de- 
posited urates copiously on cooling. The hourly quantity 
was almost three times greater than during the succeeding 
period when the acidity was restored (from nine to eleven), 
and more than three times greater than during sleep. 
The differences are not so great when the per-centage of 
uric acid in the solid residue is calculated; although 
here, also, the alkalme urime gives notably the highest 
figure. 
The urine of the alkaline tide may, therefore, in every 
sense be regarded as pre-eminently charged with uric 
acid. 
The remarkable poverty of the urine in uric acid, from 
nine to eleven, not only as contrasted with the urine of 
the alkaline tide but also with that of sleep, is probably 
closely connected with the increased excretion of uric acid 
during the preceding hours of the alkaline tide. If it be 
true, as these results lead us to believe, that a diminished 
acidity or, a fortiori, alkalescence of the urine is very fa- 
vourable to the separation of uric acid from the blood, 
and causes an increased quantity of it to pass through 
the kidneys, it follows that on the cessation of the alka- 
line tide the blood must be unusually poor in uric acid; 
and the separation of it by the kidneys therefore, on the 
