4 
Mr Barer oft, Apparatus for the 
In order to reduce the strain on the pump, due to the weight 
or disposition of the rest of the apparatus, two permanent rubber 
joints have been introduced. These are marked (a) and ( h ) on 
Fig. 1 ; (a) is shewn in detail. The glass ends are joined with 
stout pressure tubing, smeared inside and out with Canada 
balsam. The tubing is bound on with c grips \ These ‘ grips ’ I 
had made to obviate the risk of breaking the pump, which occurs 
in the binding on of wire. One of them is shewn incidentally in 
Fi g. 2. 
For drying the gases I have used a tower about eighteen inches 
in height, containing pumice wet with sulphuric acid. The sul- 
phuric acid can readily be renewed when spent, being poured in 
at k. In the lower part of the tower some sulphuric acid is 
allowed to lie, at once helping the drying process and rendering 
obvious any leak in the tap ( h ). 
If, as is necessary, more than four or five samples of blood 
are to be analysed successively, the entire acid in the drying 
chamber must be replaced without introducing air ; the apparatus 
may be set up as figured in Fig. 1. The vessel r contains 
mercury, and is so placed that with a vacuum in the pump the 
mercury rises to about the level x. The sulphuric acid is put 
in at the top of the tower and flows over the pumice. Sufficient 
is put in to fill the bulb g to the level of the tube q. Much of 
the aqueous vapour from the gases coming along m condenses on 
the surface of the sulphuric acid, forming a film of dilute acid. 
By raising the vessel r and opening the tap connecting g with 
the vacuous chamber, p, this dilute acid can be disposed of. 
Similarly, if fresh acid be put in at the top of the tower, the 
excess can be put into p, otherwise m would become closed up. 
The Receiver. 
This part of the apparatus divides itself into that for measuring 
the blood, and that for exposing it to a vacuum ; both of which 
appear illustrated in the Figs. 2 — 8. Fig. 2 refers to the measur- 
ing burette. This burette consists simply of a vertical graduated 
tube B of about 11 c.c. capacity connected at its lower end by 
means of pressure tubing with a small mercury reservoir, J. At 
its upper end the graduated tube, B, terminates in a glass tap, A, 
of peculiar construction. The stopper is shewn in detail in Fig. 8. 
Leading to the tap are two horizontal tubes, C and D. Of these C 
is connected with the cannula from which the blood is to be drawn, 
whilst D is joined at the point f to the froth bulbs shewn in 
Fig. 4. From Fig. 3 it will be obvious that the passage F may 
be continuous with either C or D, or with neither of these, 
