Q. Ann St <1>
Thursday Evg <2>
Dear Sir
I am very much obliged to you for the Comptes Rendus <3> which you sent today, as well as for the preceding one. <4>
Biot <5> seems to take a great interest in the Sensitive paper. I suppose you do not preserve the C. Rus to be bound up; if you do, pray let me know that I may return you these portions.
I recommend to you to try the sensibility of paper washed first with nitrate of silver, & then with gallic acid the latter to be pure. I have not tried it yet, but it is has [sic] been mentioned to me both by Herschel <6> & another experimenter, so that I think it must be among the best recipes yet found out.
Herschel told me that the hyposulphite washed out the chloride of silver; but I have certainly found that the hypo preserves the drawing if merely spread over it, & not afterwards washed out.
Since it remains in the paper it must form some inert white compound, with the silver, and what that is I do not clearly understand, since the Sulphuret of silver is quite black or dark brown, and quite spoils the picture when it appears, as it does sometimes.
I want to repeat Biot’s experiment with the oystershells which are lighted up by the moon’s rays <7> –
Yours very Truly
H. F. Talbot
Notes:
1. 44 Queen Ann Street: London home of the Mundy family and a frequent base for WHFT.
2. Dated 28 March 1839 by Rupert Derek Wood in 'Latent Developments from Gallic Acid’, Journal of Photographic Science, v. 28 no. 1, January 1980, pp. 36–42.
3. Comptes Rendus hebdomadaires des séances de l’ de l’Académie des Sciences.
4. See Doc. No: 03826.
5. Jean-Baptiste Biot (1774–1862), French scientist.
6. Sir John Frederick William Herschel (1792–1871), astronomer & scientist.