TALBOT1560

Monday Afternoon

Dear Sir,

If you are disengaged on Wednesday at 4 o’clock, and like to come to the Laboratory of the Royal Institution, ¹ M^r 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 Esq^re
56 Devonshire Street
Portland Place ³