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Invisible Writing Experiment from the Photographic Experiments of Sir John Herschel, October 14, 1839

preview image for Invisible Writing Experiment from the Photographic Experiments of Sir John Herschel, October 14, 1839
Inventory Number: 78062
Object Type:
Persons: Sir John Frederick William Herschel
Date Created: 1839
Accession Number: 1928-71
Brief Description: Experiment in invisible writing by Sir John Herschel, October 14, 1839, employing chemistry closely related to his photographic experiments. Two different methods are employed on this piece of paper. The first two lines have been brought out by brushing with a chemical such as hypo, and are dark brown on a brown ground. The brown chemical shows through the back, which also shows the brush marks; the linear marks around the edges of the brown are edge ripples, resulting, like the several distinctive drips below, from a very loaded brush. The rest of the paper is mauve, the writing showing as much clearer pinkish highlights, with some chemical bleeding; the back of this part is plain. Its appearance along with the Latin motto suggests an actual photographic process (employing light as well as chemicals) may have been used in this part. The four names are those of Herschel's children, who presumably witnessed the experiment. All three of Herschel's invisible writing experiments (see 23385 and 53873) are different in appearance, and thus presumably in chemistry and process. The exact chemical details are not known.

For fuller descriptive and historical commentary see narratives.
Primary Inscriptions: 'Bon Enfant | Johnny. [?]Botho | Ars Magna | Lucis et | umbrae | [line] | Oct 14. 1839 | Dolly Carry | Alex Willy' [in Herschel's hand].
Provenance: Presented by Miss Herschel and Lady Lubbock in 1928. They were the two surviving and youngest children of Sir John Herschel (Francisca and Constance).
Collection Group: Herschel's Photographic Experiments
Material(s): Paper
Height Width Depth Diameter Unit
115 94 mm


Image with multimedia irn 49593Image with multimedia irn 49594

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