TALBOT7095

[blind stamp:]
Ath^m Club 14 Dec

D^r Sir

As it is not improbable that my witnesses may be detained some hours at the Guildhall on Monday, I beg to mention that I have engaged a room for their accommodation at the Guildhall Coffeehouse corner of Gresham S^t and King S^t close to the Guildhall –

We have received notice that my opponents intend to rely among other things, on a certain experiment related by M^r Hunt in the Tran^tns of the Royal Society for 1840.¹ His paper there printed is nothing to the purpose, as my invention does not relate to the developing of images by mercurial vapour. But in a postscript quite at the end of the paper he alleges that he once made a photographic image very faintly visible on paper by immersion in a liquid. If You have the opportunity I wish you would refer to the passage –

[illegible deletion] The paper he uses is blackened with sulpher^d hydrogen, it is therefore a sulpheret of silver. His liquid is Corros^ve Sublimate and I find by exp^t that this liquid acts on every part of [illegible deletion] a paper coated with Sulpheret of Silver, whitening it (whether Light has acted or not) – He mentions no particulars of his exp^t, & [illegible deletion] the strength of his solution is not indicated. – Altho’ sulphuret of silver may be prepared in slightly different ways, I am of opinion that it would always be rapidly whitened by strong corrosive sublimate and that the circumstance of its having been first held in the vapour of iodine would in no degree interfere with this action of the sublimate. Supposing this to be correct, M^r Hunt uses a [illegible deletion] liquid which acts on every part of his paper, which is quite unlike [illegible deletion] my plan of developing an image by gallonitrate which acts only on the parts where the light has previously acted –

Yours very truly
H. F. Talbot

M^r Brande