Methodics. 



=7Г 



Fie. 1. 



My first apparatus for the determination of gas-tensions 

 in water was a tonometer constructed on the principles of 

 PflügerM: a stream of water is introduced through a narrow 

 inlet at the upper end of a wide tube. When 

 the velocity is suitably regulated it flows down 

 covering the whole surface of the wall, and 

 diffusion can take place through this surface 

 with the air in the tube. The proportion of 

 surface to volume of air is, however, in this 

 simple apparatus much too small, if a rapid 

 equalisation of tension between the air and 

 the water is desired. I have therefore modified 

 the apparatus by introducing an inner tube 

 (Л on the diagrammatic fig. 1) and allowing the 

 water to flow down simultaneously on the 

 inner wall of the primary tube and the outer 

 wall of the second. By this means I have 

 obtained a surface of 33 sq. cm. for every 

 cubic cm. of air, whereas in Pflügers appa- 

 ratus the corresponding surface was only 

 some 2—3 sq. cm. 



The details of my apparatus are of no 

 importance for the determinations of the 

 tension of carbonic acid , and they will be described elsewhere. 

 Suffice it to say that the space between the two tubes is filled 



^) Arch. f. d. ges. Physiologie. Bonn 1872 Bd. в p. 65. 



