in highly Rarefied Elastic Fluids. 



Nitrogen. 

 Duration of each experiment, two minutes. 



259 



Pressure. 



Positive 

 thermometer. 



Negative 

 thermometer. 



Difference. 



millims. 

 2 

 4 

 5 

 6 

 9 

 15 

 20 



R. 



19to2l 

 20i„ 28 

 20 „ 29 

 20 „ 3H 



20 „ 31 



21 „ 30 

 20 „ 25£ 



R. 



19 to 22 

 20i„ 25 



20 „ 24 

 20 „ 27 



20 „ 27 



21 „ 27 

 20 „ 25 



R. 



2 



3 



5 



4* 



4 



3 



i 



Hydrogen. 

 Duration of each experiment, two minutes. 



Pressure. 



Positive 

 thermometer. 



Negative 

 thermometer. 



Difference. 



millims. 



2 



5 



6 



9 

 15 

 20 

 30 



R. 



21 to 2? 



20 „ 28£ 



21 „ 29 

 21 „ 31 

 21 „ 30 

 21 „ 28* 

 21 „ 25 



R. 



21 to 25 

 20 „ 25£ 

 20 „ 25A 



20 „ 26^ 



21 „ 26 

 21 „ 26 

 21 „ 23£ 



R. 



o 



2 

 3 



3* 



4* 



4 



2* 



H 



The following gives the results of an experiment in which the 

 passage of the jet was continued for more than two minutes 

 through atmospheric air, under a pressure of 5 millims. 



Duration of 



Positive 



Negative 



Difference. 



experiment. 



thermometer. 



thermometer. 





R. 



R. 



R. 



minutes. 









2 



18 to 31 



18 to 26 



5 



4 



18 „ 37 



18 „ 30* 



H 



6 



18 „ 40 



18 „ 32 



8 



8 



18 „ 42 



18 „ 33 



9 



10 



18 „ 43 



18 „ 34 



9 



As the duratiou of the experiment increases and the absolute 

 temperature rises, the difference between the indications of the 

 two thermometers becomes relatively smaller ; the readings of 



S2 



