Dr. Meyer on the Gases of the Blood. 267 
actions of animals breathing an atmosphere very rich in oxygen 
were not observed to be perceptibly accelerated. 
I have not attempted in the present research to determine 
which of the constituents of the blood exerts this attraction on 
the dissolved gases, nor have I examined whether a compound in 
definite atomic relations, that is, a chemical combination in the 
strictest sense, is formed. At any rate the combination is ex- 
tremely unstable, as it is decomposed when the pressure of the 
free oxygen is entirely or even partially removed ; the blood gives 
up the whole of its oxygen under the air-pump. The presence 
of an excess of free oxygen is therefore necessary for the exist- 
ence of the compound. Many cases analogous to this are fami- 
liar to chemists ; such, for example, as the loss of carbonic acid 
which bicarbonate of soda suffers in air free from that gas. If 
the blood which originally has an alkaline reaction be rendered 
acid, the unstable compounds become stable, and the greater 
part of the oxygen cannot now be removed by diminution of the 
pressure: at the same time the blood changes colour. From 
this fact it is seen that the oxidizing action of the dissolved gases 
does not take place in the blood itself, but in the tissues, and 
especially in the muscles, which have as a rule an acid reaction. 
The reaction of the blood with carbonic acid differs essentially 
from that with oxygen, as a much larger quantity of carbonic 
acid is taken up from an atmosphere of this gas, independently 
of the pressure, than is the case with blood brought in contact 
with the air of the lungs. 
Defibrinated calf’s blood, which contained 33:8 per-centage 
volumes of combined carbonic acid, that is, carbonic acid only 
set free by boiling with excess of acid, measured at O° and 
0™-76, took up from a pure atmosphere of carbonic acid, 63°0 
volumes of this gas (at 12° C.) beyond the quantity previously 
absorbed, so that at the end of the absorption the blood con- 
tained its own volume of carbonic acid dissolved independently 
of the pressure. 
Eudiometric analysis has shown that the quantity of carbonic 
acid contained in arterial blood is not nearly so large as this, 
and hence it follows that the venous blood also cannot contain 
so much of this gas; for it is easy to show, from the known 
rapidity of circulation of the blood through the lungs, and the 
quantity of exhaled carbonic acid, that even under the most 
favourable conditions, the venous blood can only contain a few 
more per-centage volumes of carbonic acid than the arterial. 
The total blood circulating throughout the body, therefore, does 
not contain nearly so much combined carbonic acid as it is able 
to take up from an atmosphere of pure carbonic acid. It is 
scarcely possible to explain the absorption otherwise than by the 
