294 
DR. ROBERTS ON THE DIURNAL 
the third, fourth and fifth hours, and lasted from 
four to six hours. The effect of dinner was greater, 
as well as more prolonged, than that of break- 
fast. 
. The effect of mixed and purely animal diet seemed 
almost identical. Vegetable diet, when used on 
alternate days with mixed or animal food, had a 
decidedly feebler effect ; but when used contiuu- 
ously for several days successively its effect was 
equally powerful. 
. Alkaline urine after a meal owed its reaction to 
a fixed alkali. It was generally, but not always, 
turbid, when passed, from precipitated phosphates. 
Its odour resembled that of the fresh urine of 
the horse. It was richer in uric acid and in 
earthy and alkaline phosphates than the urine of 
fasting. 
. The depression of the acidity after a meal coin- 
cided in point of time with absorption rather than 
with digestion. The solids of the urine began to 
increase simultaneously with the declension of its 
acidity. So that the passage of food into the blood 
and the diminished acidity of the urine seemed to 
be connected together as cause and effect. 
The following deductions appear also to be warranted : — 
1. That the power of a meal to depress the acidity 
of the urine depends on its mineral constituents. 
These contain phosphoric acid and the alkalies in 
such proportion, that if we suppose them dissolved 
the alkalies invariably preponderate. Hence arises 
the alkalinity of the blood. If this be so, every 
meal that is dissolved and absorbed into the blood 
must for the time raise the alkalescence of that 
fluid above the natural level. 
