Mr. J. A. Wanldyn on the Movements of Gases. 215 



and probably even that small amount was chiefly due to the 

 disturbance on opening the tube. 



The following experiment was made with hydrogen (not dried). 

 The same tube as was used in the six first experiments was filled 

 with that gas and exposed for five seconds, with the open end 

 upwards. The residual gas after the experiment contained — 



Air 38-8 



Hydrogen 6 1*2 



100-0 



It will be obvious, on a little consideration, that the same 

 causes are in operation in this instance as in the former instances 

 where carbonic acid refused to descend. 



To show that the same phenomena occur in very wide tubes, 

 the following experiments may be cited. 



A tube, 38 millimetres in diameter, 256 # 5 cubic centimetres 

 in capacity, but of the same length (232 millim.) as the former 

 tube, was filled with carbonic acid. 



The residues in different experiments consisted of — 



Exposure of 5 seconds. Exposure of 10*5 seconds. 

 I. II. 

 Air. . . . 43-4 525 76-1 



Carbonic acid 566 47-5 23-9 



100-0 100-0 1000 



The loss of carbonic acid is therefore greater than when the 

 narrow tube is employed. We may explain this by the greater 

 extent of current, which is of necessity produced on unclosing a 

 wider tube. 



Lastly, an experiment may be brought forward in which a 

 mixture of gases was used, and in which the point aimed at was, 

 whether or not relative change takes place in the composition of 

 a mixed gas. 



The mixed gas was prepared by heating oxalic acid with 

 sulphuric acid*. An analysis previously to the experiment gave — 



Carbonic acid .... 50-62 

 Carbonic oxide .... 49"38 



100-00 



After exposure in the narrow tube opening downwards for 

 60 seconds, the product contained — 



* No doubt a trace of SO" was present, but this it was uot deemed 

 necessary to remove. 



