Some comments on JH's light and photography experiments, especially effects of different kinds of glass and fixing with ferrocyanate.

Describes mediocre results obtained using ferrocyanate of potash for fixing image. Mentions some other methods, including his favorite, common salt. Asks JH to keep these secret.

More about paper being published in both the R.S.P.T. and Athenaeum.

Finally had success washing with ferrocyanate. Wants to present note of 'his' processes to R.S.L. and so to the world.

Wishes to communicate to J. B. Biot, and so to Academie des sciences, JH's two 'beautiful' fixing methods, by hyposulfite and ferrocyanate.

Questions JH's intent to display 'photogenic drawings' to R.S.L.

Considerable comment on procedure for submitting paper to R.S.L. Urges WT to mention JH's method of washing with hyposulfite. Comments on some photographic experiments of WT.

Enlarges upon his method of using salt as photographic fixer; then asks JH to explain the chemistry thereof. Has tried Louis Daguerre's fixing process without success.

Further chemicals used for fixing, including bromide potash.

Submits payment to J. D. Roberton for 'Association' bills. Glad that ES approves of JH's draft article on terrestrial magnetism for Quarterly Review. Fears R.S.L. was premature in proposing experimental institutions; public was not prepared for such large expenditures for science. Prefers ES's suggestion of temporary magnetical and meteorological observatory. Strong disagreement from [C. J.] Riddell in America.

Departure of J. C. Ross for Antarctic expedition is approaching. Hopes that Admiralty will soon authorize R.S.L. to assist Ross in preparing instruments and coordinating global observations.

Will send two photometers and three-year supply of paper to [?]. One goes to J. C. Ross and one to F. Eardley Wilmot at Cape of Good Hope. Instructions for using photometers. Hopes [?] Robinson forwarded actinometers to Woolwich as JH directed. These should be checked at St. Helena. Instruction for using actinometers. Sent report to Humphrey Lloyd at B.A.A.S. Returns [?]'s Daguerre newspaper containing 'impudent notice about M. Pambour and his great Wheels.'

Comments on Louis Daguerre's use of muriatic ether, and encloses a photograph of hand writing.

Comments on a number of chemicals used in photography, as well as referring to JH's process of making 'enlargements.'

Consists mostly of a transcription of two short notes from J. B. Biot to JH by way of WT.

Sends a sample picture fixed by use of iodine [potash].

More photography comments. Problems with use of hyposulfite fixer. Superiority of English over Daguerreotype in being able to make copies.

Confused by an 'unfixed' photo from JH in which the image shows different effects from different colors of the spectrum. Also other comments on photography.

Sends JH a positive copy and a transparency. Remarks on JH's use of muriate of lead and asks JH to explain chemistry of it.

Advises JH not to publish any new processes in photography as there are patent problems. Comments on the Daguerreotype, and on the difficulty of preserving images in some circumstances.