Dear Sir,
I beg leave to introduce to you my Friend Major Playfair, <1> about whose Daguerreotype & Talbotype <2> labours I have so often written you.
He will be much gratified by seeing your manipulations and Instru-[ments]<3> tho’ I fear you may not have your Apparatus in Sackville Street. <4>
I had three hours hard work last night in re-examining the flames of Nitre deflagrated upon burning coals. <5> I observed again the double lines at A and B and the Group at á; but saw none corresponding with C. There were three yellow lines on the Green side of the Double yellow line D, and three beautiful Green lines which perhaps are the same as those which you observed in the Red Fire <6> of the Theatres. If they are the same this observation proves that there must be Nitre in the Composition.
I will thank you to let me know in which manner you burn the Nitre with the Sulphur as mentioned in your Paper as mentioned in the Ed. Journ. <7> No IX p. 80.
The other lines in the Red Fire are doubtless, as you suppose, the Strontia ones between C and D, and the Nitre one, which I have found to consist of A á and B.
I am Dear Sir Ever Most Truly yrs
D Brewster
St Leonards
St Andrews
Novr 14th 1841
H. F. Talbot Esqr
Notes:
1. Sir Hugh Lyon Playfair (1786–1861), military & provost of St Andrew’s University.
2. Enormous progress in photography was being made within the St. Andrews' circle.
3. Line-break, and second part of word omitted.
4. 31 Sackville Street, London residence of the Feildings, often used as a London base by WHFT.
5. See Doc. No: 04355.
6. “Fires”, flammable mixtures that burn with coloured flames. They contain fuels, oxidizers and salts of various metals to produce the desired colour. “Red fire” refers to a mixture containing a strontium salt, which would produce the red color by the molecular band emission of gaseous strontium monohydroxide (SrOH), and, if potassium chlorate were present in the mixture, of gaseous strontium monochloride (SrCl). WHFT mentions his examination of the spectra emitted by the red fires used in theatres in ‘Some Experiments on Coloured Flames’, Edinburgh Journal of Science, v. 5 no. 1, June 1826, pp. 77–82.
7. The Edinburgh Journal of Science. The volume reference may perhaps be an error for volume 5 [see note above on ‘red fires’].