THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOUKNAL OF SCIENCE. 



*& 



[FOURTH SERIES.] 



NOVEMBER 1865. 



XLIII. On some Physical Effects produced by the contact of a 

 Hydrogen-flame with various Bodies. By W. F. Barrett, 

 Assistant in the Physical Laboratory of the Royal Institution*. 



IN the spring of this year, when conducting a series of experi- 

 ments for Professor Tyndall, on the character of the radiation 

 emitted by various solids heated by means of a hydrogen-flame, T 

 noticed that on the surface of several of the substances examined 

 a deep blue colour arose as soon as the flame was brought into 

 contact with the body. Other engagements prevented a further 

 investigation of the matter until some time afterwards, when, 

 again observing the same phenomenon, I drew Professor Tyn- 

 dalFs attention to it, and he advised my pursuing the subject. 

 For this purpose he kindly placed sufficient time at my disposal, 

 for which, and other marks of kindness, I may here perhaps be 

 allowed to express my sincerest thanks. 



A careful examination of this blue coloration showed that it 

 occurred only when the flame came into actual contact with the 

 substance, the colour being restricted with great precision to the 

 place where the hydrogen was in combustion; accordingly it 

 gave in section a faithful image of the construction of the flame. 

 This singular appearance was invariably of a rich blue tint ; 

 its production was instantaneous, but its duration was generally 

 short, for it disappeared after a few seconds' exposure when the 

 flame continued to play upon one spot, although it was immedi- 

 ately restored by shifting the position of the jet to an untried 

 portion. The hydrogen in some experiments burnt from a 

 small orifice in a brass tube, and in others from a platinum jet ; 



* Communicated by the Author. 

 Phil Mag. S. 4. Vol. 30. No. 204. Nov. 1865. Y , 



