and Nitrogen Vapour at the Boiling-point of Oxygen. 365 



Table III. Density of Oxygen Vapour at its Boiling-point under 

 Diminished Pressure. 



In reducing these observations the following corrections were 

 involved: a correction of 0'0014 gramme to 0-0015 gramme due to 

 imperfect exhaustion of the A flask while being weighed as empty ; 

 the correction due to the neck of the flask between the mark and the 

 stopcock not being at 90 -5 amounted to 0-00003, 0-00007 gramme 

 and was practically negligible ; the volume of the flask, which, when 

 corrected for temperature, was 314-398 c.c., had to be further corrected 

 for excess of external pressure over internal pressure by amounts 

 varying from 0*0551 c.c. to 0'0742 c.c. If the first three experiments 

 are averaged (the pressures being so near), the weight of a litre of 

 oxygen at 90 0< 5 absolute under a pressure of 282*5 mm. would be 

 1'5982 grammes. The ratio of this density to the value previously 

 found for one atmosphere pressure, viz., 4-42 grammes, is 2'765, and 

 the ratio of the pressures is 2-690. It appears that the ratio of the 

 change of density of the vapour of oxygen at 90'5 absolute, under 

 variable pressure, is greater than the ratio of the change of pressure. 

 It is clear, however, that it would be necessary to work upon a 

 larger scale in order to get satisfactory vapour densities at low tem- 

 peratures under pressures below that of the atmosphere. 



The following table gives the observations on the density of nitro- 

 gen vapour at the boiling-points of liquid oxygen and liquid air 

 respectively ; the first two were made in oxygen, the last four in air. 

 The symbols used are the same as before, except that d is the calculated 

 density at T absolute and 760 mm. and v is l/d. 



Table IV. Density of Nitrogen Vapour at the Boiling-point of 



Oxygen. 



