M. W. Feddersen on Thermo diffusion of Gases. 



Time. 



Cold side. 



Hot side. 



Observed. 



Calculated for 

 10 minutes. 



Observed. 



Calculated for 

 10 minutes. 



h ni h m 

 p.m. 2 50 to 3 40 



3 40 „ 4 20 



4 25 „ 4 45 



5 „ 5 30 



5 30 „ 6 10 



6 30 „ 7 



7 „ 7 15 



millims. 

 250 

 tube wanting. 

 200 

 200 

 130 

 220 

 73 



millims. 

 50 



ioo 



677 

 325 

 73-3 



48-7 



millims. 

 20 

 125 

 65 

 30 

 50 

 60 

 23 



millims. 

 40 

 31-2 

 32-5 

 10-0 

 12-5 

 200 

 15-3 



Duriug the night the lamp went out, and cooling took place. 



A.M 



.6 50 



to 



7 50 





8 









9 



9 





9 









12 









12 









1 









1 







>> 



1 



30 



285 



265 



tube wanting. 



225 



40 



47 5 

 442 



*37 ; 5 

 13-3 



tube wanting. I 



immovable. 

 415 I 231 



10 1-7* 



immovable. 



We see here that in every instance the motion observed in the 

 drop followed the direction through the plug from the cold to 

 the hot end. From the fact that the drop on the cold side 

 always moved quicker than that on the hot side, it must be 

 concluded that, besides the phenomenon of gas-displacement, 

 there was also a special absorption with the charcoal, greater 

 than that which appeared in like manner to take place with the 

 spongy platinum. 



Silicic acid. — The arrangement of the experiment was the 

 same as with the two last-named substances. The length of the 

 plug (of silicic acid in powder fresh from incandescence) in 

 the tube of 12^ millims. diameter amounted to 110 millims. 

 After the action of the difference of the temperatures (about 

 200° and 8°) had lasted continuously some 3^ hours, the follow- 

 ing observations were made : — 



Time. 



Cold side. 



Hot side. 



Observed. 



Calculated for 

 10 minutes. 



Observed. 



Calculated for 

 10 minutes. 



h m h m 



p.m. 5 10 to 6 



6 10 „ 6 30 



6 30 „ 7 10 



7 10 „ 7 30 

 7 30 „ 8 



millims. 

 65 

 90 

 125 

 56 

 64 



millims. 

 130 

 45 

 31-3 

 28-0 

 21-3 



millims. 

 60 

 75 

 140 

 59 

 75 



millims. 

 120 

 375 

 35 

 29 5 

 25 



* From 12 o'clock the end of the tube on the hot side was closed by a 

 drop; the difference of pressure produced by the process was not sufficient 

 to overcome the capillary attraction at that place. 



