Viscosity of Hydrogen, Nitrogen, and Oxygen. 595 



was again liquefied. This operation was repeated over and 

 over until the gas was found by analysis to be pure. Then the 

 gas was introduced into the compression-suction apparatus C 

 (in fig. 2) through the stopcock S 6 . The stopcocks S 2 to S 5 

 controlled the shunt passages, as in the other two apparatus. 

 The analysing apparatus consisted of a pyrex tube D 

 connected through a ground joint to a volumetric bulb E, 

 which was in turn connected to a MacLeod gauge. D was 

 filled to two-thirds of its length with granulated copper and 

 surrounded by an electric heater (not shown in fig.). For 

 analysis S 7 was closed, and both the bulb E and the tube D 

 were evacuated through S 9 . When the pressure inside was 

 reduced to somewhat less than 1 mm. mercury, the tube D 

 was heated up in order to drive out whatever moisture there 

 might have been in the copper. The evacuation was continued 

 until discharge could hardly pass between the terminals ot 

 the vacuum tube V. Then the pressure-gauge was read 

 and the stopcocks S 8 S 9 were closed. Then a certain amount 

 of the gas to be analysed was introduced into E through S 7 . 

 Then S 7 was closed and S 8 opened and the gas in E was 

 allowed to go into D, where it was absorbed by the copper 

 which had in the meantime been heated up to about 

 500 degrees centigrade. When the gas was pure, both 

 the vacuum tube V and the pressure-gauge showed the 

 same indications as before when the gas had not been 

 introduced into E. 



Table III. — Viscosity of Oxygen. 



No. of Temperature Temperature Mean 



observation. at beginning. at end. Temperature. ??Xl0 7 . 



°c. °c. °c. 



1 22-990 23-000 22-995 2041-75 



2 23-080 23-050 23-040 2045-2] 



3 22-995 23-000 22-998 2042-14 



4 23-010 23-C00 23*005 2044-24 



5 23-010 23-010 23-010 2041-95 



6 22-99;) 22-980 22-985 2043-21 



7 23-000 23-000 23000 2041 21 



8 22-995 23-000 22-998 2042-01 



9 22-980 22-970 22-975 2043-15 



10 22-980 22-980 22-980 2045-07 



11 23-005 23-010 23-008 2041-25 



12 23-010 23-020 23015 20-12-12 



13 22-990 22-980 22-985 2043-04 



14 23-010 23 010 23-010 204105 



15 22995 23-000 23998 2041-05 



16 23-000 23000 23000 20!! -CO 



17 23-010 23-020 23015 2042-50 



18 23005 2:, -010 23*008 2041-4] 



19 22-990 22-980 22-985 2041*42 



20 22-995 23-010 23'008 2042*36 



Mem 23-00] 204235 



