London
March 28. 1839
Dear Sir
I found in one experiment that glass placed under the paper, produced a considerable change in the tint, which became redder: the reddened part corresponding to the shape of the glass proved it to be owing to that. I do not see whence this arises. In taking the image of a man with a red waistcoat, from painted glass, the waistcoat came out red also in the image, not a bright colour, but a decided tint.
I am glad that you agree with me respecting the attempt of Messrs Willmore, Havell &c. to take out a patent for a process which I have myself executed 5 years ago at Geneva. <1>
In the Literary Gazette of next Saturday, I shall insert a letter to the Editor <2> on the subject. They have however, abandoned the patent.
I am very glad to know that an addition of ammonia will prevent the formation of sulphuret of silver, which circumstance has occurred to me several times & spoiled my pictures. Accurate experiments on the new sensitive paper gave the other day, the time of discoloration in daylight (not sunshine) two seconds, to three seconds – Biot finds it nearly instantaneous, & is making a great many expts on it. He says “Je ne crois pas qu’il soit possible de trouver une substance plus sensible”. <3>
Do you think he means by this to express an opinion that it is equal in sensibility to Daguerre’s substance?
The art of expanding or diminishing [illegible deletion] an etching by the Camera Obscura is one which I have long contemplated, but to you belongs the merit of having first realised it. I did not speak of it in my memoir to the R.S. because I had laid down a rule for myself not to speak of what I had not tried.
Wheatstone <4> proposed to me the other day to dispense with a lens altogether & employ a radiant point of light, but this, if obtained from the Sun, will not be sufficiently divergent, if from galvanic light, &c, will probably be deficient in intensity of Chemical Rays– Perhaps the enclosed paper <5> may interest you, on the applicability of sensitive paper to Meteorology.
Today I tried with my Bromine paper to copy my neighbour’s house. Notwithstanding the unfavourable weather the result was very encouraging. In some places the individual bricks are given which compose his façade. I am therefore very desirous of ascertaining the proper mode of fixing a Bromine picture, without injuring its delicate shades; I wish you would make some experiments thereon.
Yours most truly
H. F. Talbot
Else Havell will be taking out a patent for it.
Notes:
1. William Havell (1782–1857), and James Tibbetts Willmore (1800–1863), discussed but never executed a patent for reproducing etchings on glass on photogenic drawing paper (essentially the cliché verre process). See articles in the The Literary Gazette and Journal of belles lettres, science and art, 30 March and 6, 13 April 1839.
2. See Doc. No: 03852.
3. ‘I do not know whether it is possible to find a more sensitive substance’. Letter from Jean-Baptiste Biot (1774–1862), French scientist, not located.
4. Sir Charles Wheatstone (1802–1875), scientist.
5. Enclosure not located.