1904.] Physical Constants at Low Temperatures. 253 



Table II. — Nitrogen. 



No. 



Description. 



r. 



V. 



T. 



p. 



d. 











o 



mm. 







1 



At B.P. of N . . 



-195° 5 



15-192 



16-1 



747 







•8042 



2 



At M.P. of N. . 



-2105 



16 592 



15-95 



747 







8792 



3 



At B.P. of N . . 



-252-5 



18-911 



14-65 



761 



1 



•0265 









(solid) 











The same notation is used as in Table I. 



The volume of the flask at 14° -2 C. was 22*1454 c.c. 



Coefficient of expansion of glass, 0*0000250. 



Weight of 1 litre of nitrogen at 0° C. and 760 mm., 1-2564. 



Table III.— Hydrogen. 



No. 



Description. 



r. 



Y. 



T. 



V- 



d. 













mm. 





1 



At B.P. of H .. 



-252°5 



18 -051 



14-6 



760 



0-07001 



2 



H under 76 mm. 



-258 -29 



19 -447 



14-6 



760 



-0754| 



3 



H under 10 mm. 



-259 -9 



19 -597 



14 -3 



762 



-0763 









(solid) 









The same notation is used as in Table I. 



The volume of the flask at 14°-2 C. was 22'1454 c.c. 



Coefficient of expansion of glass, 0"0000250. 



Weight of 1 litre of hydrogen at 0° C. and 760 mm., taken as 

 0-0899. 



2. It is of advantage to estimate the effects of an error, or of any 

 reading that may have been taken roughly. Taking the notation 

 already employed, and putting w for the weight of 1 litre of the gas 

 at 0° C. and 760 mm., then the weight of gas used is 



W 



Vp273 



760 (273 + T) 



and if V be the volume of the flask up to the mark at some ordinary 

 temperature T ° C, and V its volume at T' the temperature Centigrade 

 of the observations, then 



y,_ y 



1+/8T ' 



where fi is the cubical coefficient of expansion of the glass. Hence, 

 the density of the substance at the time of observation is 



T 2 



