TALBOT7088

M^r Maskelyne

Friday Ev^g
Dec 8

D^r Sir

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. M^r 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 exp^ts 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