122. Regent S^{t <1>}
18^th April 1849

To H. F. Talbot Esq^r

Sir

I did not see the person who called for Hellings account

I am told that he insisted that it was a private transaction thereupon your address was given It shall be attended to. Sir David Brewster’^{s <2>} portrait touched up by Preston will be worth one guinea for a single impression subsequent copies fifteen shillings each. –

Enclosed is a piece of iodized paper having a defect which is very common & which was supposed to be due to the presence of iron I find it to be copper combined with zinc (brass) Ammonia produces the blue colour characteristic of copper. –

With the aid of a microscope I have dissected out the nucleus of the “star” The action of ammonia & the yellow metallic lustre prove it to be brass – probably from the under plate of the paper makers engine.

I am sorry to say that it is not easily removed by Acids or Ammonia It is some satisfaction to know that it is not iron. –

I am still perplexed with the points of resistance in the fibres of the paper which give a porous appearance to the image. I anticipate that we shall find this latter defect is chemical & not dependent on the “make” of the papers. The presence of Hyposulphite or some other chemical salt still produces a change in the positives we think even after distilled water has been used.

Several Amateurs also complain Something might be learned from an examination of pictures made & fixed by yourself some years since.

I remain Sir yours most obediently
T A Malone

[envelope:]
H F Talbot Esq
Lacock Abbey
Chippenham

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Notes:

1. Sir David Brewster (1781–1868), Scottish scientist & journalist.

2. The London address of the Sun Picture Rooms, proprietor, Nicolaas Henneman (1813–1898), Dutch, active in England; WHFT’s valet, then assistant; photographer.