28th Oct 1851
I beg to inform you that I
this yester day went to Messrs Horne & Co <1> who showed me the process of transferring the Picture to paper which is somewhat as follows.
A paper is first prepared of Muriate of Knighter <2> (which was already prepared for the process because it was necessary it should be dry) - A solution of Ammoniacal Nitrate of Silver is then poured upon the paper which is then put into a Frame and the Glass Picture put upon it, the reverse side of the Picture being downwards the picture being tightly screwed upon the Paper. - The paper in the frame is then exposed to the Sun for about a quarter of an hour and the impression on the paper is made by the action of the Sun. - To complete the impression it is then dried with Gas light and "set" which is done by pouring suphotile of Soda <3> upon it and afterwards washed in water <.> Mr T stated that it was necessary so to wash it but did not shew this part. - I am not quite certain that I state the Chymical terms correctly but you will I hope comprehend what I intend to convey - Mr T called the process the Collodian process. <4> [illegible deletion] He gave me the enclosed printed instructions and [illegible deletion] told me that a perfect treatise <5> is expected to be out in a week or two. - They do not make a positive picture direct upon paper but only by transfer
I am Sir
Your most Obdt Servt
B H Hack
1. Horne, Thornthwaite, & Wood, opticians & suppliers of photographic materials. Talbot considered taking legal action against them and they testified against him in Henderson's trial.
2. Could be read as Brighter. Neither makes any sense - Knighter was probably nitre, but saltpetre could not have a chloride.
3. i.e. fixed with hyposulphite of soda
4. i.e. wet collodion - Horne & Thornthwaite were one of the first suppliers of collodion to the photographic trade.
5. The firm issued a number of booklets encouraging the use of their products, using authors such as Robert Hunt and Thomas Hennah.