Discusses how best to simulate the light at a particular point on the earth’s surface using coloured glass; considers sunlight as composed of three "principles", varying in proportion according to latitude, which affect germination, lignification, and floriation.
Mentions RH’s book on light [Researches on light in its chemical relations, 2d ed. (1854)]. Asks about coloured glass used in experiments on plants.
Informs CD which colours of glass accelerate germination, lignification, and floriation; advises CD on obtaining such glass and offers his help in any experiments.
Mentions experiments on plants involving coloured glass. Encloses correspondence from glass maker and asks advice.
Encloses a sketch of the principal events in his life [for RH’s memoir on CD in Walford, ed., Portraits of men of eminence (1863–7)].
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Has been experimenting with photographic papers. Outlines some of his experiments. Has prepared some papers for sale.
Is grateful for his letter. Sends some of his photographic sheets. Now uses a different chemical to prepare his papers. Will be pleased to send JH his results and to receive a copy of the memoir in due course.
Would like JH's account of his own method of fixing a photograph as noted in his memoir. Singular phenomenon of the Daguerreotype. Hopes to produce a photographic paper to equal the silver plate before the month has expired. Will let him know when his process is complete.
Exchanging further information on several aspects of the photographic process [see RH's 1840-4-15].
Is grateful for the handsome manner in which JH has acknowledged RH's work. Would be willing to prepare a memoir for the R.S.L. Does Louis Daguerre's patent affect RH's manufacture of photographic papers? Has not studied the bromnets so far, but has studied the effects of bromine on plates. Comments on his results.
Sends his paper for communication to the R.S.L. Will send some more examples later as his camera has developed a defect.
Returns the photographic drawings of W. H. Fox Talbot with many thanks. Fears for their permanence. Has produced similar pictures himself acting on bromide of silver with hydrocholoric acid. Has had trouble with his periscope lens.
Was gratified to receive his memoir and to find many of his doubts corrected by JH's experiments. Hoped to enclose some sulphuretted papers but the chemicals went astray in the post. Intends to follow JH's example and precipitate a glass.
Is grateful for the suggested emendations to his paper. Comments on the action of iodine on silver and its oxide. When can he expect publication of his paper? Has noted a peculiar property in the calorific rays when copying engravings. Encloses some Daguerreotype papers.
Is grateful for referring him to Capt. Ludlow. Has now moved himself to Falmouth. What does JH think of the chances of success of a popular book on photography? He is contemplating the idea. Hears that J. B. Biot considers the production of colored drawings impossible, but is not convinced himself. Encloses description and drawing of a very clever instrument.
Has not lately done much work in photography, except to work with paper treated with vegetable substances.
Returns with grateful thanks the example of photographs recently sent him. They open up a new field of curious processes. Will not have much time this summer for photographic experiments as he is carrying out a series of investigations into the air of mines. Has been experimenting with the cyanurets.