366 Specific Volumes of Oxygen and Nitrogen Vapour. 



In reducing these observations, the following corrections were 

 involved : a correction of O002 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 

 temperature T amounted to '000 14 gramme and was practically 

 negligible; the volume of the flask, which only required to be 

 corrected for temperature, was 314-398 c.c. 



Experiments 1, 2 were made with liquid oxygen taken to be. at 

 temperature 90 0> 5 absolute. The experiments 3, 4, 5, 6 were made 

 in one and the same sample of liquid air, with rising temperature. For 

 these temperatures, obviously only a few degrees below the boiling- 

 point of oxygen, the ordinary gaseous laws may be held to apply, 

 in order to determine their values. Thus we may employ the 

 formula 



90-5 



T = v 



256-833' 



where 256-833 is the mean of the volumes of Nos. 1, 2, to get the 

 temperature of the last four experiments. The values thence obtained 

 are entered in column T. 



The first two experiments made with liquid oxygen give a ratio of 

 the nitrogen densities from my own values of 3 -088, the absolute 

 temperature ratio being 3 '01 7 ; my values for the ratio of the oxygen 

 densities for the same range of temperature being 3'091 as previously 

 deduced. We may safely assume that if the density of nitrogen, jvere 

 observed at its boiling-point it would deviate asnmch from the" 

 ordinary gaseous laws as oxygen. Further, the specific volume of 

 nitrogen at its boiling-point of 78 absolute, would from the above 

 formula be 221-3 as compared with 226'2, the similar value found for 

 oxygen. 



The general inference to be drawn from these preliminary experi- 

 ments is that reliable vapour densities may be determined at very low 

 temperatures. There seems to be no reason why the vapour density 

 of hydrogen at its boiling-point should not be accurately ascertained ; 

 only, as in this case the internal pressure in the weighing flask would 

 amount to nearly 15 atmospheres, it would be advisable to construct 

 the flask of some metal or alloy. A flask of the size used in the oxygen 

 experiments filled with the vapour of hydrogen at its boiling-point 

 would be equivalent in weight to between 4 and 5 litres of hydrogen 

 at the ordinary temperature and pressure, and such an amount of 

 material ought to give density results at the boiling-point of hydrogen 

 of considerable exactness, notwithstanding the great manipulative 

 difficulties that would necessarily be involved in the execution of such 

 a determination at 21 absolute. 



