296 



EXPERIMENTAL INVESTIGATIONS. 



it and charged with pure nitrogen, to a level marked some- 

 where below the capsule ; the wires w w' are now connected 

 with a voltaic battery of sufficient power fully to ignite the 

 wire d. 



(46.) After the wire was ignited the volume of the gas 

 gradually increased ; when the original volume was doubled 

 the gas was examined. It had a strong disagreeable odour, 

 very similar to that of coal-gas ; it burned with a blue flame, 

 slightly tinged with yellow : placed in an eudiometer, such as 

 I formerly described,* and mixed with hydrogen, it under- 

 went no alteration. Two volumes of it, mixed with one 

 volume of oxygen, contracted one-sixth of the whole volume, 

 and, subsequently agitated with lime-water, contracted two- 

 sixths more, lining the tube with a crust of carbonate of 

 lime. The residual gas was nitrogen. It was thus clear that 



Fig. 4 . 



the vapour of camphor was decomposed by the ignited wire 

 into carburetted hydrogen and carbonic oxide, and the ana- 

 logy is too direct to leave any doubt that these gases were 

 also formed in Experiments (43) and (44) by the influence of 

 the platinum foil and spongy platinum. 



The apparatus (fig. 3) offers a most convenient means of 

 decomposing volatile hydrocarbons, and possibly other sub- 

 stances. 



(47.) Portions of oil of turpentine and of cassia were 

 now placed in capsules (fig. i), weighed and exposed each to 

 an atmosphere of nitrogen in the large tube of a gas battery, 



* Phil. Mag., Aug. 1841, p. 99 ; and Phil. Trans., 1843, P- IO 5- 



