and Diathermancy of Air and Hydrogen, 



419 



were regarded as equally reliable and acute observers, and yet 

 the results were so widely different. 



My own observations on the diathermancy of moist air agree 

 pretty closely with those of Magnus. Unfortunately, the season 

 of the year prevented the application of tensions above a tem- 

 perature of 13° ; I purpose to continue ray experiments in this 

 direction under more favourable conditions of temperature. 



For the experiments which hitherto have been made, the 

 above-described apparatus with the glass cylinder was em- 

 ployed. The soldered junction was 45 millims. below the 

 bottom of the brass vessel. The numbers obtained are tabu- 

 lated with those for carbonic acid and for hydrogen ; those for 

 the latter are the results of a repeated examination. 



Table X. 



T. 



T'. 



t. 



r. 



z'. 



millims. 



100 TT 



t 



Hydrogen, dry. 



62-5 

 470 

 390 



515 

 38-5 

 325 



40-5 

 324 



26-7 



18-4 

 150 

 125 



7 

 7 

 



1-5 

 15 



7590 



454 

 46-3 



46-8 



Carbonic Acid, dry. 



620 



820 



530 

 66-5 



43-2 8-3 

 580 110 



5 



7 



7500 

 7500 



19-2 

 190 



Moist Air. 



81-0 



850 

 870 

 700 

 86-0 



69-0 



73 5 

 79-0 

 55-7 

 720 



60-2 



57-15 

 620 

 442 

 590 



23 1 



(23-5) 



19-4 



125 



8-7 



11-5 



6 



6 



7 



65 



6 



8-2 (9°) 



12-9 (12°) 

 756-6 (10°'9) 

 756-6 (10°-7) 

 756-6 (13°-7) 



390 



340 

 201 

 19-7 

 19-5 



The numbers of the last column are throughout comparable 

 with the corresponding ones obtained in preceding experiments 

 with a distance of 45 millims. between the brass plate and the 

 junction, and according to which, for dry air of atmospheric 



density, — - — =20*7, for vacuum — - — =43-4. The radia- 

 ting brass bottom was clean and polished ; the soldered junc- 

 tion was covered with lampblack, as in the experiments quoted 

 in Table V. The carbonic acid, prepared from sodium carbo- 

 nate by sulphuric acid, was dried over calcium chloride. 



2E 2 



