OF THE URIC ACID IN THE URINE. 
245 
When vegetable food only was taken the contrast with animal food was very marked. 
The urine did not decrease in acidity to the same degree ; though it became neutral, 
it did not become highly alkaline. The increase in the acidity of the urine was by 
no means so marked as the decrease of the alkalescence. The acidity of the urine 
was rather higher with the vegetable food than it was with animal food. 
III. As to the effect of dilute sulphuric acid. 
Dilute sulphuric acid, taken in large doses, did not produce any very decided re- 
sults. Nine drachms of dilute acid in three days slightly diminished the decrease in 
the acidity of the urine after food. The acidity before food was very slightly, if at 
all, increased thereby. 
When the acidity of the whole quantity of water passed in twenty-four hours, for 
three days when no sulphuric acid was taken, is compared with the acidity when 
nine drachms of dilute sulphuric acid were taken, the increase is sufficiently distinct 
to prove that the acid does pass off in the urine. 
The result of these experiments is, that the acidity of the urine is always changing, 
and that the changes depend on the state of the stomach. 
When much acid is in the stomach, the acidity is then diminished. As the acid 
returns from the stomach, the acidity of the urine increases, and usually readies its 
highest limit before food is again taken. 
Animal food causes a greater oscillation in the acidity of the urine than vegetable 
food does ; and when no food is taken the oscillation is very small. 
The diurnal variations in the acidity of the urine make it highly probable that 
corresponding variations occur in the alkalescence of the blood ; such diurnal varia- 
tions being produced by the quantity of acid poured into the stomach for the purpose 
of dissolving the food. 
When the food is irritating, or the stomach in an irritable state, much acid is 
poured out, and the effects on the blood and urine are more marked than they are 
when less acid is secreted. 
Dr. Prout’s capital experiment of hydrochloric acid in the stomach during diges- 
tion, gives the key to these diurnal variations of the acidity of the urine, and may 
lead to the discovery of the diurnal variations of the alkalescence of the blood. 
Part II. — On the Simultaneous V aviations of the amount of Uric Acid and the Acidity 
of the Urine in a Healthy State. 
The variations which occur in the acidity of the urine are of themselves of very 
great interest, whether in relation to health or to disease ; whilst the determination 
of the amount of uric acid and acidity at the same time directly solves the question, 
whether the acidity of the urine depends on the uric acid ; and thus alone can clear 
views of the causes of the precipitation of the urate of ammonia in the urine be ob- 
tained. Moreover, it is necessary to trace fully the variations of the uric acid in 
health before deductions can safely be made regarding the variations of the amount 
of uric acid in different diseases. 
2 K 
MUCCCXLIX. 
