22 Messrs. L. Hill and M. Greenwood. Influence of [Oct. 6, 



into glass bulbs with rubber connections, care being taken to drive out any 

 air bubbles that may be present. The rubber junctions are then clamped, 

 and the dissolved gas subsequently pumped out by means of Hill's blood- 

 pump, the volume determined, and the mixture analysed by the potash and 

 pyrogallic acid method. 



In this manner, a sample of urine, passed since the pressure limit had 

 been reached, was available for analysis, and a series of specimens could be 

 obtained. It was first, of course, necessary to determine the amount of gas 

 dissolved by the urine under normal pressure conditions. Six analyses 

 were made, and the mean volume of dissolved nitrogen per 100 c.c, reduced 

 to 760 mm. and 0° C, was found to be 1*14 c.c. The individual observations, 

 made at different times and under different circumstances, exhibit only 

 a small, range of variation, they are 1*21, 119, 0*97, HO, 1*31, 1*07, 114. 

 The coefficient of variability determined by one of us (M. G.) is only 

 9-5699 ±1-8799. 



We are thus entitled to assume that, in our own cases, the coefficient 

 of solubility for atmospheric nitrogen under normal barometric pressure, and 

 at body temperature, is between 011 and 0*12. 



We next determined the changes in the amount of dissolved nitrogen with 

 varying pressures. The following are the results of a typical experiment : — 



Experiment 31, 31.5.06. 



M. G-. — compressed to +30 lbs. in 10 minutes (2.50 p.m.). 

 The bladder was then emptied, and at 2.55 the bladder was emptied again, 

 135 c.c. of urine being passed, and Sample 1 was taken. 

 2.56 — decompression commenced. 



3.20 ( + 15 lbs.) — the bladder was emptied again (320 c.c). 

 3.45 — decompression completed, bladder emptied again (310 c.c). 

 4.1 — another sample taken (135 c.c. passed). 

 At 4.55 and 6.10 other samples were taken. 



Analyses. 



Sample. 



Time and pressure. 



Percentage 



of 

 nitrogen. 



Calculated N per cent., 



supposing urine 

 followed the pressure. 



1 

 2 and 3 



4 



5 



6 





2 522 



2-373 



1-107 

 1-023 



1-1x3 = 3-3 



1-1 



1-1 

 1-1 



Were spoiled 



At normal pressure, 16 minutes after decom- 

 pression 



245 minutes later 





