Fig 4. 



J'x 



Mr. Grove on the Decomposition of Water by Heat, 23 



The tubes are much more easily preserved from cracking, 

 and the ignition better kept up with oil on the exterior than 

 witli water, but as in many of these experiments I might have 

 been considerably mis- Fig. 3. 



led by a crack in the 

 glass, or a bad seal- 

 ing of the wire, al- 

 lowing a portion of 

 oil to enter the tube, 

 I used water in the 

 greater number of 

 them until I was as- 

 sured of the phaenomena. 



The apparatus, fig. 3, is superior in one respect 

 to fig. 2, even for experiments over water, as the 

 wire being situate below the volume of gas, the circu- 

 lation is more rapid. This object may also be effected 

 by employing the form of eudiometer, fig. 4, in which 

 the loop of wii*e is near the centre of the tube, so as 

 to be just above the surface of water in the tube; 

 there are, however, some difficulties of manipulation 

 with this form, which render it practically of less 

 value than fig. 1. 



Binoxide of nitrogen o\ev distilled water contracted 

 differently in proportion to the heat of the wire ; in 

 the best experiment it contracted to one-third of its 

 original volume; the residual gas was nitrogen. 

 Nitric acid was found in solution in the water. 



Over mercury the effects were nearly the same ; the mer- 

 cury was attacked, and the orange fumes of nitrous acid were 

 visible. 



Protoxide of nitrogen was decomposed into nitrogen and 

 oxygen ; the volume increased by 0*35 of the original volume ; 

 I could not get the full equivalent proportion, or 0*5 of oxygen. 

 Carbonic acid underwent no perceptible alteration. 

 Ammonia increased to double its original volume ; it was 

 now no longer absorbable by water, and gave three volumes 

 of hydrogen, plus 1 nitrogen. 



Olejiant gas contracted slightly, deposited carbon, the residue 

 being hydrogen and olefiant gas, more of the former in pro- 

 portion to the heat, but I could not succeed in entirely de- 

 composing it. 



Nitrogen suffered no change. 



Oxygen gave a very slight contraction, amounting to jV^h 

 of its volume ; the oxygen employed was very pure, obtained 

 from chlorate of potash and manganese, and also from water 



uL 



