If you are disengaged on Wednesday at 4 o’clock, and like to come to the Laboratory of the Royal Institution, <1> Mr Faraday & I are going to repeat the experiment we tried today on the flame of Cyanogen <2> which proves of so extraordinary a nature that I am about to contrive some apparatus to view it more distinctly.
The Prismatic Spectrum formed by this flame is crossed by innumerable dark lines like the Solar Spectrum, & there are two broad dark belts in the violet, as in solar light.
This phenomenon appears to me remarkable as it differs so decidedly from any other flames I have seen.
Believe me Yours most truly
H. Fox Talbot
J.F.W. Herschel Esqre
56 Devonshire Street
Portland Place <3>
1. Royal Institution, London.
2. In May of 1827, WHFT met with Prof Michael Faraday (1791–1867), scientist, and Herschel to examine the spectra emitted by Cyanogen and ‘Fires’, flammable mixtures containing metal salts that can occur in various colours characteristic to each metal. These experiments were an extension of WHFT’s work published as, ‘Some Experiments on Coloured Flames’, Edinburgh Journal of Science, v. 5 no. 1, June 1826, pp. 77–82. [See Doc. No: 00309].