338 MM. H. Sainte-Claire Deville and Troost on the 



estimate), the platinum tube into which dry air is sent yields 

 nothing but nitrogen and water* ; at the same time the number 

 of bubbles of hydrogen which issue from the tube leading from 

 the annular space is seen to diminish f. Moreover, when the 

 temperature of 1100° (by estimate) is exceeded, the gases leaving 

 the platinum tube contain an appreciable quantity of hydrogen. 



If the apparatus is allowed to cool, the same effects are repro- 

 duced, but in the contrary order, the gas which traverses the 

 platinum tube returning to pure air. 



During the whole course of the experiments, the hydrogen 

 which leaves the annular space is entirely absorbed by oxide of 

 copper. 



If at the moment when the temperature is very high we sud- 



* Composition of the Air at regularly increasing Temperatures, starting 

 from Red Heat. 



Oxygen 

 Nitrogen . . 



19-0 

 81-0 



100-0 



16-7 

 83-3 



100-0 



15-5 



84-5 



100-0 



12-3 



877 



100-0 



10-5 



89-5 



8-8 

 91-2 



5-9 

 94-1 



3-0 



97-0 



100-0 



100-0 



100-0 



100-0 



100-0 



100-0 



Starting from 



about 



Hydro 



Nitrog 



1100° 



gen. . . 

 2n . . . 



and pa 



ssing a 

 ] 



little 

 1-3 



98-7 



oo-o 



beyond this temperature, 



21-9 

 78-1 



100-0 



Quantities of Water obtained per hour, air passing at the rate of about 

 one litre per hour. 



89 milligrammes. 

 183 



282 



554 



This water contains a small quantity of nitric acid. 



If carbonic oxide is substituted for hydrogen, this gas does not penetrate 

 in any perceptible quantity into the platinum tube. The air which leaves 

 the tube possesses very nearly the normal composition — 



Oxygen 207 20'6 



Nitrogen 79-3 79*4 



1000 100-0 



Liebig's tubes, through which the air and carbonic oxide which issue 

 from the apparatus are passed, do not change their weight, and the gases 

 are perfectly dry. 



These trials have been made on two tubes of about 1 millim. thick, 

 heated for a length of 15 centims., or the quarter of the whole length. 

 These tubes, intended to be used for the concentration of sulphuric acid, 

 hold a vacuum, and have been tested under great pressure at ordinary tem- 

 peratures. 



f The air and hydrogen are supplied by apparatus yielding strictly 

 regular currents. 



