S^6 Mr Blackadder on the Constitution of Flume. 



(?d curves variously modified, and whidi proceed from the same 

 cause as the pulsatory motion of the flame. On approaching a 

 flame to this vapour it readily catches fire, and burns with a 

 white flame, which is in an inverted position. The tube may 

 be bent so as to give an upright flame, and by having several 

 tubes in the form of branches, all on the same level, the lamp 

 may thus be surrounded with jets of white flame. This va- 

 pour may also be made to protinide from the tube in a cylin- 

 drical form, like a white taper, with a flame confined to its up- 

 per extremity. As the ambient air is usually agitated, this va- 

 poury taper exhibits singular motions ; and as its flame may 

 be tinged successively with various colovu's, h^ slight alterations 

 or additions at the wick from which the vapour proceeds, it 

 presents rather an interesting appearance. When a mixture of 

 volatile oil is used to produce this vapour, it affords* an oppor- 

 tunity of illustrating the theory of certain meteors supported by 

 M. de Luc and others. Narrow cylindrical masses rise in the 

 air, and when these are inflamed at one of their extremities^ 

 they burn rapidly, giving the appearance of luminous balls tra- 

 versing or descending through the air. On introducing the ex- 

 tremity of the glass-tube into a glass receiver, the vapoiu' falls to 

 tlte bottom of the vessel, being, as formerly stated, more like a 

 milky liquid than a gaseous body ; and any quantity may thus 

 be collected. White light is extricated when it is exploded 

 with atmospheric air ; but, when agitated with water, until it is 

 quite transparent, it gives a blue flame. It differs in no res- 

 pect from the vapour obtained from the centre of the flame in 

 the way formerly described ; and when the circular wick is pro- 

 perly adjusted, it appears to consist of carburetted hydrogen, 

 heavily loaded with oil in tlie state of vapour ; but the wick 

 ma,y be So arranged as to cause an admixture of carbonic acid 

 l^as, either in very minute quantity, or so great as to render the 

 vapour incombustible, as it issues from the central tube. When 

 oil is burned, the white part of the abstracted vapour conden- 

 sies into an amber coloured oil ; and, when tallow is burned, it 

 is deposited in the form of a white powder, which adheres to 

 the sid^ of the vessel, or forms a cake on the surface of water. 

 The inhalation of this vapour, even when much diluted, pro- 

 duces an oppressive headache ; and hence it is not advisable ta- 



