Chapter II 



GASES CONTAINED IN THE BLOOD AT DIF- 

 FERENT BAROMETRIC PRESSURES 



Subchapter I 



OPERATIVE METHODS AND EXPERIMENTAL 

 DISCUSSION 



I think I should, at the beginning of this chapter, describe the 

 apparatuses used for the extraction of the gas of the blood, and 

 indicate with a few details the manner in which I use them. I 

 shall also place here the account of the control experiments which 

 I made to study the degree of precision which can be attained by 

 such researches. 



The first of the indispensable instruments is the syringe by 

 means of which one takes from the blood-vessel a measured quan- 

 tity of blood to be conveyed to the extraction apparatus. 



The model upon which I fixed after many attempts is repre- 

 sented in Figure 23. 



Its body is of thick glass, with ground bore and fittings, for 

 without this precaution the glass bursts spontaneously at the least 

 change of temperature. This body is held by and solidly cemented 

 into two steel end-pieces, fitted with leather gaskets and fastened 

 to each other by 4 strong rods of steel. 



The piston, so arranged as not to turn of itself, is mounted on a 

 rod equipped with a special screw thread, which in its whole course 

 makes only one turn and a half. The upper part, closed by a screw, 

 can be removed and the syringe opened so that the piston can be 

 completely withdrawn for cleaning. This upper part is pierced 

 by a small orifice, through which is introduced a little water which 



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