Radcliffe Observatory Oxford
Jany 4th 1855
Dear Sir
Since my return to Oxford I have been so much engaged that I have not yet had time to try all the experiments you wished
I have tried Iodised collodion versus Iodised paper – both on Glass and treated by the collodion process, with very good success.
I have also converted some of your iodised paper into soluble paper (collodion) by means of nitric acid – but can detect no difference which can be attributed to the iod: silver, this latter remains unaffected by the nitric Acid and is left behind on treating the paper afterwards with alcohol and ether – The resulting collodion contains no iodine.
I have not succeeded yet in getting a satisfactory film of iodide of silver on a sheet of pure collodion which has been separated from the glass. but do not in the least doubt of ultimate success as soon as I can give a little more time to it.
Perhaps the following experiment is worth mentioning – it has, as yet, been only tried roughly, but the success has been very good.
I took a sheet of paper and dipped it into concentrated nitric Acid, and in a few minutes removed it, and washed & dried it.
(this rendered it soluble paper)
I then dipped the sheet into iod: potass: dried it, and then cut it in half.
one half I gummed on to a piece of glass.
one half I dissolved in ether containing a little alcohol, and coated a piece of glass with the resulting iodised collodion
These two pieces of Glass were dipped into a bath of Nit. silver containing Gallic acid – exposed in the camera and developed will gallo nitrate. I obtained a satisfactory picture on each.
I think a modification of this experiment would settle the question whether the Gum paper has any Photographic Action per se; as, if it has the action would doubtless be evident without having previously dissolved it in ether. My next experiment will be to compare the sensitiveness of two sheets of paper – one of which has been previously treated with concentrated Nitric Acid, and the other not.
I remain Sir yours truly
William Crookes
H. F. Talbot Esqre
[envelope:]
H. F. Talbot Esqre
Laycock Abbey
Chippenham
Wilts.