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 lt 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), 6(2) and b(S) (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 



