Radcliffe Observatory

Oxford

Dec^r 3^rd 1854.

Sir

I received your letter, with the negatives &c on Thursday last. I will endeavour to come to town on Thursday or Friday next and will not fail to call on Mr Botton. In answer to your enquiries: –

1. I have practised the Calotype process since the spring of 1851.

2. For upwards of a year I worked according to the specification, and after having overcome the difficulties of manipulation which it shares in common with every chemical operation, I found it remarkably easy and certain. I can produce specimens in which your specification was exactly followed: but in general I used the Gallo-nitrate rather more dilute, and employed a glass rod instead of a brush, for spreading. Since the receipt of your letter I have again taken two or three pictures by it, following the directions scrupulously.

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4. I perfectly agree with what Sir D. Brewster says about the Collodion process. perhaps the following experiments may show the similarity of the Calotype and Collodion processes in a more striking manner. –

I have taken a sheet of paper and saturated it with iodised collodion; then, sometimes after a lapse of several hours, sometimes immediately, have dipped it into nitrate of silver; after remaining there for a few minutes I have dipped it into water, dried it with blotting paper, brushed Gallo-nitrate over the surface and proceeded afterwards as in the Calotype process. By this means I have succeeded in obtaining portraits &c as quickly and as sharp as when I employed the Collodion on Glass. I have also obtained equally good results by exposing the Collodionised paper in the Camera as soon as it was taken from the bath of nitrate of silver. Gallic acid in these cases answered better than Pyro Gallic, for developing with.

5. I never for a moment doubted your claim to the Calotype Process as described in the specification, nor the novelty of the invention, and

6. To the best of my knowledge that is the opinion of such scientific men and others of my acquaintance who are capable of judging.

I have printed off copies of the 4 negatives you enclosed and will bring them with me. One of them will not suffer by comparison with the best Collodion picture that I have seen –

I remain, Sir

Yours very truly

William Crookes

H. F. Talbot Esq^re