BAIRD &. TATLOCK (LONDON) LTD. 



790 



790 s Dr. Leonard Hill Gas Pump, for analysis of the gases of the blood. Price, on stand, with 

 three eudiometers (H), and six blood receivers (F) . . . . . . each 



ihis pump is so contrived that it can give qualitative results of sufficient accuracy with ten grammes 

 of blood. The pump is admirable for the purposes of class demonstrations on account of its simplicity, cheapness, 

 and rapidity of action. 



In research work the pump is equally useful, for while the working errors are under i per cent., the physio- 

 logical errors are reduced to a minimum". These latter errors always arise from the withdrawal of those large 

 quantities of blood which are required by the use of all other blood-gas pumps. 



The pump as shown in the figure consists of a mercury reservoir (A), about 300 cubic centimetres in capacity, 

 which is connected with a second reservoir (B) by means of 120 centimetres of pressure tubing. The upper end 

 of the reservoir (B) is closed by a three-way tap (D). By means of this tap the reservoir (B) can be put in con- 

 nection with either the tube (E) leading to 'the blood receiver (F), or with the tube (c) leading to the eudiometer 

 (H). The tubes (E) and (c) are made of manometer tubing. The blood receiver (F), which also acts as the froth 

 chamber, consists of three glass bulbs connected by short and wide junctions. To either end of the blood 

 receiver is fixed a piece of pressure tubing, provided with a screw clip. This tubing is of excellent quality, 

 and is too thick to collapse under atmospheric pressure. 



Half-a-dozen such blood receivers are allotted to the pump for the purpose of obtaining successive samples 

 of blood. 



In using the pump, the successive manipulations are as follows : A blood receiver is affixed to the end 

 of the tube (E), and the receiver is elevated into the position indicated by the dotted outline. The reservoir 

 (B) is then put in connection with the tube (E) by means of the three-way tap (D), the reservoir (A) is raised 

 above the pump, and the whole system is filled with mercury to the top of the blood receiver (F). The screw 

 clip on the rubber tube at the upper end of (F) is then closed, and the reservoir (A) lowered until the blood 

 receiver is exhausted, except for 2 or 3 cubic centimetres of mercury, which are purposely left within. The 

 screw clip on the lower end of (F) is next Closed, and the blood receiver now clipped at either end, exhausted, 

 detached from tube (E). and weighed. A sample of blood is then collected in the following way : The arterial 

 or venous canula is filled with blood, and immediately afterwards pushed into the rubber tube at the end of the 

 blood receiver, as far as the closed screw clip. Before the insertion of the canula, the end of the rubber tube 

 is compressed with the fingers to exclude the air within it. A sufficient quantity of blood is now withdrawn 

 by opening at the same time the screw clip, and the clip placed on the vessel of the animal. The blood is 

 defibrinated by shaking it with the mercury left within the blood receiver for that purpose, and the latter is 

 then again weighed. The weight of the sample of blood is then obtained. The blood receiver is next affixed 

 once more to the tube (E), in the dependent position shown in the figure, and the tube (E) is exhausted. Finally, 

 the screw clip between (E) and the blood receiver is opened, and the gases are withdrawn and collected in the 

 eudiometer. Since the blood receiver hangs freely from the tube (E) by means of a piece of rubber tubing, it 

 can be both immersed in warm water, and shaken to facilitate the complete escape of the gases. The bulbous 



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CROSS STREET HATTOTST GARDETST, E-C- 



164 



