380 On Hespiralion. 



two minutes, and contained nearly 100 cubic inches of 

 azote more than could be accounted for in the oxvjrcn cm- 

 ployed ; hence it is plam, that a large proportion ot" the 

 increase is evolved in the first periods of the process. 



Our attention was particularly directed to this point in 

 the following experiment. The oxygen, procured as usual 

 from hyperoxygenized muriate of potash, was found to 

 contain four per cent, of azote ; the experiment was con- 

 ducted in the same manner as the preceding ones, except 

 that the tubes of the gasometers were filled with oxygen, 

 and the gas was not merely passed once through the lungs, 

 but breathed backwards and forwards in order to prolong 

 the duration of the experiment, which began and ended 

 with a forcible expiration. Portions of the respired gas 

 were preserved for examination from each of the gasoiive* 

 lers. in the folloA'in<i order: 



The portion of oxygen remaining in tlie water gasometer of 

 the original quantity, not employed in the exjicriinent, was 

 found upon trial to contain four per cent, of azote, as before. 



Summary of the Experiment. 



Cub. Inches Cub. Inches Defi- 

 Bar. Therm, of Oxygen ct'C.iscx- ciency. Time, 

 inspired. pircd. 



29*9 51 2663 2544 124 13 minutes: 



here the deficiency was greater than we had ever remarked 

 before.; but on passing an equal quantity of conurion air 

 from the water gasometer, and registering it in the mercu- 

 rial ones, we were satisfied thai the apparatus was quite 

 perfect. It is, however, to be considered, that the respi- 

 ration in this case was not natural, and that some small 

 degree of force was required when the inspirations and ex- 

 pirations were made in the mercurial gasometers, which 

 renders this experiment rather different from those which 

 had preceded it ; and it appc;irs to us probable, that a por- 

 tion of air was forced into the extremuies of the bronchia, 

 which could not be suddenly expelled by the strongest at- 

 tempts at expiration. Hence also, perhaps, the constant 

 though smaller deficiency, even when the air was only once 



passed 



