Analysis of the Gases in Small Quantities of Blood. 7 
sents the receiver in the usual forms of gas-pump, the blood can 
be allowed to pass into any one of a number of vacuous chambers, 
and the gases from any chamber can be drawn off at will into the 
pump. 
Fig. 4 represents the apparatus in question in which six 
samples of blood can be analysed. 
For purposes of description the whole of this apparatus will be 
spoken of as a “ receiver/’ the part between the tap (a) and the 
tap (b) (that part which concerns itself solely with one sample 
of blood) as a “ chamber,” each chamber being made up of three 
“ froth bulbs.” The two parallel tubes cd and ef are each termed 
in the following description a “ main,” following the analogy 
which the drawing presents to a system of electric lighting. The 
tube cd is termed the “ gas-main,” and e/the “blood-main.” The 
receiver stands in the vertical plane, mounted on a wooden stand, 
which is screwed on to the stand of the pump (Fig. 8). The 
“ blood-main,” made of two-millimetre bore tubing, is horizontal 
at the bottom, the “ gas-main ” made of broad tubing is at the 
top. Leading from the one to the other, there are arranged “ in 
parallel” six chambers A (1), A (2), etc. The junction of each 
chamber with the “ blood-main ” is a tap b 1} b 2 , etc. These 
taps are of special construction, and are shewn in detail in 
Figs. 5, 6, and 7. They are three-way taps, and a glance at the 
figure will shew that when the stopper is turned with the handle 
parallel to the “ main,” there is a path for the blood to run 
straight through the stopper, the tube in which becomes neither 
more nor less than part of the “main” itself. When the tap 
is turned through an angle of 90° as shewn in Fig. 6, any blood 
or mercury running along the main to the tap must go into 
the corresponding chamber, and there only. When it is required 
to transfer blood from the burette to any chamber, say b (4), the 
stoppers of b (1), b (2) and b (3) (that is, of those taps situated 
between b (4) and the point f which is attached to the burette) 
are turned as in Fig. 7, the stopper of the tap b (4) is turned as 
in Fig. 6, and one continuous tube from the burette to the 
chamber A (4) is formed, along which the blood, and some 
mercury to wash it over, must necessarily travel. Once the 
blood and a cubic centimetre or two of mercury have gone into 
the “chamber” the tap b( 4) is closed, -the handle being turned 
at an angle of 45° to the “ main,” and as the chambers are used 
in the reverse order to that in which they are numbered in 
Fig. 4, this tap is never again touched during the experiment. 
In the apparatus described the capacity of each chamber is 
200 cubic centimetres. With receivers of this size it is necessary 
to hold warm sponges round the uppermost froth-bulb while the 
blood is entering the chamber, otherwise the whole chamber fills 
