THE CHEMISTRY OF THE SECRETIONS. 
849 
ascertained an increase of nitrogen in the gases expired by an 
animal which breathes pure oxygen. The greater acidity of 
the urine is due to the presence of an organic acid in more 
than the normal quantity. M. Ritter believes this to be 
lactic acid, which is known to be a product of the oxidation of 
nitrogenous substances. 
Muscular activity acts nearly in the same w r ay as the 
inhalation of oxygen. Byasson had already determined that 
it augmented the urea, uric acid, and chlorides; whilst brain- 
work augmented the urea in a more marked degree, as well 
as the sulphates and phosphates. M. Ritter is not com¬ 
pletely in accordance with that author. His researches have 
borne upon the influence of walking exercise, the brain- 
work remaining the same. Oxidation is increased, but in a 
mode differing according to circumstances. A moderate walk 
by an individual rising from complete rest is followed by an 
increase of the quantity of nitrogen eliminated by the urine; 
the proportion of urea to uric acid increases by nearly one 
half. If the individual be already leading an active life, the 
products of oxidation are slightly increased, but in an almost 
identical proportion. If the individual make a forced march, 
the total quantity of azote diminishes; but the relation of 
the urea to the uric acid increases, as after the inhalation of 
pure oxygen. 
Before determining the action of protoxide of nitrogen 
on the urine, M. Ritter investigates that which it exercises 
on the blood; and he shows that this gas is dissolved in the 
blood in greater quantity than in serum deprived of blood- 
corpuscles ; but that all the gases, even carbonic acid and 
hydrogen, displace it easily, whilst it only displaces these 
gases incompletely and at the end of a very long time. At 
the same time, in a long series of experiments, M. Ritter 
proves that the oxidising action of the gas, at the temperature 
of the human body, is not comparable to that of atmospheric 
air. Whether, then, protoxide of nitrogen be breathed, or 
water charged with the gas be drunk, it is found that the 
quantity of carbonic acid expired is always diminished; that, 
in the urine, the quantities of urea, uric acid, nitrogenous 
matters, are increased, but in a degree proportionate to 
the quantity of the urine itself, which is also augmented. 
There is a diuresis here, which must probably be re¬ 
ferred to a special physiological action of the protoxide of 
nitrogen. 
The admirable researches of Claude Bernard have taught 
us that the oxide of carbon deprives the blood-corpuscles of 
their faculty of absorbing oxygen. This gas, then, ought, a 
