44 Queen Ann S^{t <1>}
Feb^ry 20^th 1839

Dear Sir

I am very much obliged to you for a sight of your photogenic drawings, some of which possess great beauty, and give promise of still more. I have found out how to use the ferrocyanate, ^<2> viz. by washing the picture with it, & then washing out, 3 times successively–

If there is a meeting of the R. Soc^y tomorrow, I intend to request M^r Christie to read a note, ^<3> briefly mentioning the nature of my processes; ^<4> which will then be free to all the world to adopt, or to find out better ones for themselves.

The weather both yesterday and today was of the most Antiphotogenic description, in London.

Believe me Yours very truly
H. F. Talbot

P.S. I hope you received my letter of yesterday

---

Notes:

1. 44 Queen Ann Street: London home of the Mundy family and a frequent base for WHFT.

2. WHFT utilised a method of neutralising the silver salts in a bath of potassium ferrocyanide. True cyanates do not feature in photographic chemistry, being uncommon and rather unstable. In this case, references to ‘cyanates’ or ‘ferrocyanates’ should be read as meaning ‘cyanides’ or ‘ferrocyanides’. Thiocyanates, also earlier called sulphocyanides, did have some photographic uses.

3. Samuel Hunter Christie (1784–1865), mathematician & Secretary of the Royal Society, see Doc. No: 03813.

4. Photogenic drawing

.