Manchester Mevwirs, Vol. Ivii. (1913), iV^^. 13. 3 



inserting the stopper when the tube was gradually with- 

 drawn without stopping the exhalation. After removing 

 the stopper under a concentrated solution of brine which 

 had been saturated with carbon dioxide at the ordinary 

 tennperatures and pressures, a rubber cork provided with 

 two glass tubes was then introduced into the mouth of the 

 bottle under the liquid in the brine trough, the air dis- 

 placed into a 100 c.c. gas burette and the COo absorbed by 

 transferring the air into an absorption tube containing 

 caustic potash (which surrounded the measuring tube to 

 take up less space in the box). It was found, however, that 

 although the results so obtained were as a whole relatively 

 good, this method of collecting the exhaled air tended to 

 make the individual conscious that he was breathing, and 

 consequently the breathing tended to become abnormal. 



The final method adopted for collecting the exhaled 

 air was by breathing into a metallic gas-holder dipping 

 into brine, similar to that used in gas works, the gas- 

 holder being counterpoi.sed by weights. This device made 

 it more easy to breathe naturally into the apparatus as the 

 whole of the residual air from the mouth and throat was 

 also introduced, and nothing required attention except 

 the tap which was opened or closed as desired. 100 c.c. 

 of the mixed air from the gas-holder, after throwing awa)' 

 the first portion to clear the tubes, was taken into the 

 gas burette and analysed as above described. 



Humidity. 



The humidity of the air was determined by the wet 

 and dry bulb thermometers having a scale of 20 degrees 

 to the inch. I do not consider these thermometers satis- 

 factory. Subsequent experiments, in which very delicate 

 thermometers were used having a scale of 20 degrees to 

 'j\ inches, gave wonderfully accurate results when com- 



