Mr Talbot's Experiments on Coloured Flames. 79 



in which there was a very bright yellow line, indicating the 

 combustion of the sulphur. I thought it a point ot consider- 

 able interest to determine, whether this yellow ray was iden- 

 tical with that afforded by the flame of alcohol containing 

 salt, and, with that view, I placed such a flame behind the 

 other, their light passing through the same opening ; so that, 

 if the rays were of a different nature, two yellow lines should 

 be seen in the spectrum ; but if identical, then only one. I 

 found, upon trial, that the rays coincided ; and I obtained a 

 further confirmation of this, by inflaming the nitre and sul- 

 phur, mixed up with a quantity of salt ; the effect of which 

 was, not to produce a second yellow line in the spectrum, but 

 to increase greatly the brilliancy of the original one. The re- 

 sult of this experiment points out a very singular optical ana- 

 logy between soda and sulphur, bodies hitherto supposed by 

 chemists to have nothing in common. 



3. There are other means of procuring the same light 

 which I shall briefly mention If a clean piece of platina foil 

 is held in the blue or lower part of a gas flame, it produces 

 no change in the flame, but if the platina has been touched by 

 the hand, it gives oft* a yellow light which lasts a minute or 

 more. If it has been slightly rubbed with soap, the light is 

 much more abundant, while wax, on the contrary, produces 

 none. Salt sprinkled on the platina, gives yellow light while 

 it decrepitates, and the effect may be renewed at pleasure by 

 wetting it. This circumstance led me to suppose that the 

 yellow light was owing to the water of crystallization, rather 

 than to the soda, but then it is not easy to explain why the 

 salts of potash, &c. should not produce it likewise. Wood, 

 ivory, paper, &c. when placed in the gas flame, give off (be- 

 sides their bright flame) more or less of this yellow light which 

 I have always found the same in its characters. The only 

 principle which these various bodies have in common with the 

 salts of soda, is reciter ; yet I think that the formation or 

 presence of water cannot be the origin of this yellow light, be- 

 cause ignited sulphur produces the very same, a substance 

 with which water is supposed to have no analogy. * It is al- 



* It may be worth remark, though probably accidental, that the speci- 

 fic gravity of sulphur is 1.99, or almost exactly twice that of water. 



