6 Escape of Gases through Capillary Tubes. [1817. 



continued, after the force was removed, diminished as the spe- 

 cific gravity increased ; as for instance, in 



Carbonic acid it continued 6 seconds. 



Common air 8 ,, 



Coal-gas 10 ,, 



Hydrogen gas 17 



There is therefore every reason to believe, that the actual re- 

 lative mobilities of the gases are inversely as their specific 

 gravities. 



These experiments have been carried much further, in con- 

 sequence of some peculiar results obtained at low pressures ; 

 but as I have not been able to satisfy myself respecting the 

 causes, and have probably taken a wrong view of the pheno- 

 mena, I shall refrain from detailing them, and merely observe, 

 that there is no apparent connexion between the passage of 

 gases through small tubes and their densities at low pressures. 

 Olefiant gas then passes as readily as hydrogen, and twice as 

 rapidly as either carbonic oxide or common air, and carbonic 

 acid escapes far more readily than much lighter gases. Similar 

 results are also obtained by diminishing the bore of the tube, 

 and then even at considerable pressures, the effect produced 

 by mobility alone is interfered with by other causes, and dif- 

 ferent times are obtained. These anomalies depend, probably, 

 upon some peculiar loss or compensation of forces in the tube, 

 and offer interesting matter of discussion to mathematicians. 



Experimental Observations on the Passage of Gases through 



Tubes*. 



IN a previous communication I have noticed briefly some 

 curious effects which take place when gases are passed through 

 tubes at low pressures. They consist in an apparent inversion 

 of the velocities ; those which traverse quickest when the pres- 

 sure is high, moving more tardily as it is diminished, until they 

 are among those which require the longest time in passing the 

 tube; thus with equal high pressures equal volumes of hydro- 

 gen gas and olefiant gas passed through the same tube in the 

 following times : 



* Quarterly Journal of Science, vii. 106. 



