and Nitroyen Vapour at the Soiling-point of Oxygen. 363 



In reducing these observations the following corrections were in- 

 volved : a correction of 0-0015 gramme, due to imperfect exhaustion of 

 the flask A while being weighed as empty ; the correction due to the 

 neck of the flask between the mark and the stopcock was negligible ; 

 the volume of the flask when corrected for temperature was 315-973 c.c., 

 and when it was necessary to correct further for excess of external 

 over internal pressure, the values were as given in Column V in the 

 last four experiments this correction varied from about 0*059 to 

 0-073 c.c. 



The first three experiments give a mean value of 1*260 grammes, at 

 standard temperature and pressure, as the weight of a litre of nitrogen. 

 This is about a quarter per cent, higher than the accepted value of 

 1-257. The extreme variation in the individual experiments is about 

 half a per cent. The average value of the results under about one-third of 

 an atmosphere is 1*266 grammes the tendency under the low pressures 

 being to make the density half a per cent, higher. Considering that 

 in the actual low-temperature experiments the mass of gas to be 

 weighed would be at least three times greater, it was inferred that in 

 spite of difficulties of manipulation and corrections the results might 

 be anticipated to lie within a half per cent, of the true value. 



The following table gives the results of six experiments made on 

 the density of the vapour of oxygen at its boiling-point taken as 90 -5 



Table II. Density of Oxygen Vapour at its Boiling-point. 



absolute, and under atmospheric pressure, where p, p\, T lt a, I, are the 

 same symbols as used in the previous table, d is the calculated density 

 at 90-5 absolute and 760 mm., and v is the specific volume l/'rf. 



In the above reductions the following corrections were involved : 

 0-002 gramme due to imperfect exhaustion of A flask while being 

 weighed as empty 0-0002 gramme due to the contents of the neck 

 of the flask between the mark and the stopcock not being at 90 -5 -. 

 the volume of the flask up to the mark contracted at 90 *5 to 

 314-398 c.c. no correction was necessary for compression. 



Thus the mean weight of one litre of oxygen vapour at 760 mm. 

 and 90 -5 absolute is 4-420 grammes, and the specific volume is 



2 c 2 



