60 



M. W. Feddersen on Thermo diffusion of Gases. 



The accessory tubes were taken away at night; yet the 

 difference of temperatures was maintained. 



Time. 



Cold side. 



Hot side. 



Observed. 



Calculated for 

 10 minutes. 



Observed. 



Calculated for 

 10 minutes. 



h m h m 



a.m. 6 40 to 7 10 



7 10 „ 7 40 



7 40 „ 8 10 



8 10 „ 8 40 



8 40 „ 9 10 



9 10 „ 9 40 



millims. 



103 



75 



74 



50 

 tube wanting. 



millims. 

 34-3 

 250 

 24-7 

 16-7 



millims. 

 116 

 80 

 82 

 59 

 83 

 76 



millims. 

 38-7 

 26-7 

 273 

 197 

 27-7 

 25-3 



Of absorption, such as took place with charcoal and spongy 

 platinum, there is here no trace perceptible. 



Calcined magnesia. — The experiment was made with freshly 

 heated magnesia under the same conditions as the last-mentioned 

 substances. In the tube of about 12J millims. diameter the 

 length of the plug was at first 100 millims. 



Time. 



Cold side. 



Hot side. 



Observed. 



Calculated for 

 10 minntes. 



Observed. 



Calculated for 

 10 minutes. 



h m h m 

 5 30 to 5 40 

 5 40 „ 5 50 



5 50 „ 6 



6 „ 6 15 

 6 15 „ 6 30 

 6 30 „ 6 35 

 6 35 „ 6 50 

 6 50 „ 7 



millims. 

 145 

 140 

 132 

 214 

 tube wanting. 



m it 



205 



142 



millims. 

 145 

 140 

 132 

 143 



i37 

 142 



millims. 

 tube wanting. 



» » 



95 



135 



134 



43 



154 



tube wanting. 



millims. 



95 

 90 

 89 

 86 

 103 



For the following experiments a part of the magnesia was ex- 

 tracted from the tube, in consequence of which the length of the 

 plug was reduced to 40 millims. 



Time. 



Cold side. 



Hot side. 



Observed. 



Calculated for 

 10 minutes. 



Observed. 



Calculated for 

 10 minutes. 



millims. 

 228* 

 212 



h m h m 

 7 30 to 7 35 



7 35 „ 7 40 



millims. 

 142 

 140 



millims. 

 284 

 280 



millims. 

 114 

 106 



* In support of the quantity of gas supposed to have passed through the 

 cross section of the plug in the unit of time, let it be remarked that a cylin- 

 der of about 13 millims. length in the accessory tubes represents a volume 

 equal to that of a cylinder of 1 millim. length in the diaphragm-tube. 



