PROCEEDINGS 
OF THE 
Cambridge ||l)tloso|)bka( Socictn. 
Apparatus for the Analysis of the Gases in Small Quantities of 
Blood. By Joseph Barcroft, King’s College. [With Plate I.] 
The present communication consists of an account of an 
apparatus for the quantitative estimation of the oxygen and car- 
bonic acid in the blood coming from a particular organ. 
The general principle of analysis used in all estimations of 
the two gases is that of exposing the blood to a vacuum and 
removing the gases which it gives off by means of a mercurial 
pump. 
So far, however, this principle has been only applied with 
accuracy when considerable quantities of blood (30 — 50 c.c.) have 
been available for each analysis, and in the case of blood drawn 
direct from a living animal it has been necessary to take it from 
some large vessel when the rate of flow is rapid. 
These experimental difficulties have excluded the possibility 
of analysing the blood from special organs except in a few cases. 
Among these cases may be mentioned the experiments on the 
respiration of muscle by Ludwig, Schmidt and Sczelcow. 
The object of the research for which my apparatus was 
devised is a comparison of the arterial and venous bloods entering 
and leaving the submaxillary gland, according as the gland is or 
is not secreting saliva. 
In this case the samples of blood available are, as a rule, 
about in volume 8 c.c., though sometimes only 5 c.c., and the 
length of time taken to collect such a sample is 3 — 4 minutes. 
The object before me then has been to construct an apparatus 
in which the working error is about Jth of that of existing ones, 
1 
VOL. XI. PT. I. 
