3 io EXPERIMENTAL INVESTIGATIONS. 



bad sealing of the wire, allowing a portion of oil to enter the 

 tube, I used water in the greater number of them until I was 

 assured of the phenomena.* 



The apparatus, fig. 3, is superior in one respect to fig. 2, 

 even for experiments over water, as the wire being situate 

 Fig. 4. below the volume of gas, the circulation is more rapid. 

 This object may also be effected by employing the 

 form of eudiometer, fig. 4, in which the loop of wire 

 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. I. 



Binoxide of nitrogen over distilled water con- 

 tracted 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 nitro- 

 gen. Nitric acid was found in solution in the water. 



Over mercury the effects were nearly the same: the mercury 

 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 3 volumes of 

 hydrogen, plus I nitrogen. 



Olefiant gas contracted slightly, deposited carbon, the 

 residue being hydrogen and olefiant gas, more of the former 

 in proportion to the heat, but I could not succeed in entirely 

 decomposing it. 



Nitrogen suffered no change. 



Oxygen gave a very slight contraction, amounting to ^th 

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

 from chlorate of potash and manganese, and also from water 

 by electrolysis : no change in properties was perceptible in 

 the oxygen after its exposure to the ignited wire. This con- 

 traction I incline to attribute to a slight portion of hydrogen 

 present, which view will, I think, be considered as strengthened 

 by the effect of the ignited wire on hydrogen, to be presently 



