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supplied by Mr. Dancer, a jet of oxygen being surrounded by 
an annular jet of the coal gas. Mr. Dancer has further 
improved the jet by allowing the oxygen pipe to project 
beyond the hydrogen, and by not contracting the aperture of 
the hydrogen pipe. 
Mr. Alfred Fryer exhibited the light which he had 
explained, and the effect produced was very striking. 
Professor Roscoe read the following communication, by 
Professor Clifton and himself, entitled, ee On the Effect of 
Increased Temperature upon the Nature of the Light Emitted 
by the Vapour of certain Metals or Metallic Compounds.” 
In a letter communicated to the Philosophical Magazine 
for January last, we stated that in examining, with Steinheil’s 
form of Kirehhoff and Bunsen’s apparatus, the spectra pro- 
duced by passing the induction spark over beads of the 
chlorides and carbonates of lithium and strontium, we had 
observed an apparent coincidence between the blue lithium 
line, which is seen only when the vapour of this metal is 
intensely heated, and the common blue strontium line called 
Sr §. We further stated that on investigating the subject 
more narrowly by the application of several prisms and a 
magnifying power of 40, we came to the conclusion that the 
lithium blue line was somewhat more refrangible than the 
strontium S, but that two other more refrangible lines were 
observed to be coincident in both spectra. Having con- 
structed a much more perfect instrument than we at that 
time possessed, we are now able to express a definite opinion 
on the subject, and beg to lay a short notice of our observa- 
tions before the Society. Our instrument is in all essential 
respects similar to the magnificent apparatus employed by 
Kirehhoff in his recent investigations on the solar spectrum 
and the spectra of the chemical elements. It consists of a 
horizontal plane cast iron plate, upon which three of Steinheil’s 
Munich prisms, each having a refracting angle of 60°, are 
