I forgot to return to you the specimen you sent of the Positive Process, <1> pray remind me of it when you See me, as you may wish to produce it in Court <2> – It is quite good enough for an illustration of the process.
In my letter of today, <3> I might have explained some things better, I will therefore revert to the subject of Reades process <4> –
He brushes ordinary paper with Gallonitrate (without acetic acid, tho’ I dont know whether it makes any difference) He obtains a
certa[blot] certain amount of Visible result which he employs – not knowing that of the existence of an invisible image, in some cases capable of development.
Now I find that if iodised paper is excited with gallonitrate washed and dried, it is highly sensitive – This is [illegible deletion] the Sensitive Calotype paper of my patent
But if ordinary paper is [illegible deletion] brushed over with Gallonitrate and dried, it is insensible to light: that is to say, there is no visible darkening in 1 hour’s exposure at window. There is no comparison possible in this case with the iodised paper. But if the ordinary paper be not dried, light acts upon it slowly. Mr Reades own method is to brush on the paper with nitrate only, dry it completely, then wash it with Gallic acid and use it wet. This answers better, but is still very slow, I doubt the possibility of a Camera picture in any reasonable time.
I tried these expts with Whatman’s paper & Turner’s paper, which I thought were the best.<5> –
As my counsel wishes to show the great difference made by my iodised paper, I should wish you to try a comparative Experiment <6> or two.
Yours vy truly
H. F. Talbot
1. See Doc. No: 07083 and Doc. No: 07085.
2. Story-Maskelyne had been asked to be a witness for Talbot in the trial concerning his patent, in which he sought to prove that he had invented the Calotype process and that the collodion process was covered by the Calotype patent, and thus not a new invention. The trial took place from Monday 18 to Wednesday 20 December 1854. In 1852 Talbot had reluctantly relinquished his photographic patents as far as amateur photography was concerned, though he retained them regarding professional portraiture. He won several injunctions against professional portrait-photographers who infringed them, and in 1854 he sought to obtain one against Martin Laroche, a professional photographer who took portraits using the collodion process, who, he claimed, had infringed two important elements of his patents. He then found himself having to defend his right to his patents and even his claim to the invention of photography on paper. [For an account of the patent cases, and the opposition to Talbot’s patents, see H. J. P. Arnold, William Henry Fox Talbot: Pioneer of Photography and Man of Science (London: Hutchinson Benham, 1977), pp. 198–209.]
See 3. Doc. No: 07087.
4. Rev Joseph Bancroft Reade (1801–1870), microscopist & photographer. For an account of his process, see Doc. No: 07059. The opponents of Talbot’s photographic patents asserted that Reade had invented the Calotype process before him.
5. Whatman’s Turkey Mill paper, a writing-paper made in Maidstone, Kent, was favoured by Talbot for photographic use. Its wove surface provided a uniform base for prints and a patternless density for negatives, and it had good wet-strength, although small variations in texture and chemical content could cause problems when the paper was used in photography. The gelatin size suited photographic chemistry better than the rosin used in some other papers, particularly Continental ones. It was generally watermarked with the year of manufacture and certain years were sought after. The paper manufacturer, G W & R Turner, Chafford Mills – owned by the brothers George William Turner and Richard Turner at Chafford, Penshurst, Kent, with another mill at Bermondsey, Surrey. In 1830, they dissolved their partnership, with Richard taking Chafford and George William taking Bermondsey. Their only other known brother, William, may have been involved, but he died in an insane asylum in 1838.
6. See Doc. No: 07087.