Reply to JT's 'Remarks on Radiation and Absorption.' Calls non-absorption of air and vapor key to understanding meteorological phenomena. Remarks on 'radiant heat' from moon.

Thanks for and comments on paper and lectures on 'diathermancy &c' of gases, scientific teaching, and solar chemistry. Regrets that JT mentioned all names connected with light research except JH's. Remarks on absorption of light, molecular vibrations.

Remarks on JT's papers on radiant heat and related role of moisture. Will send requested sample of rock salt. Explains difficulties using it and hopes JT will have better success, perhaps even repeating JH's experiments.

Sends copy of JT's '3rd Memoir,' along with specimens of liquid mercury ethyl and mercury methyl from discoverers Edward Frankland and B. F. Duppa.

Believes Michael Faraday's boro-silicate of lead has not been used for telescopes, but JH and others have tried using it for other optical purposes. Describes method for producing veinless flint glass.

Continues experiments with carbonic acid and electric light [see JT's 1868-11-30], suggesting possible cause of blue cloud color and eventual whitening of light.

Asks JH to review paper on blue color of sky, polarization of skylight, and polarization of light by cloudy matter.

Is delighted with JH's exposition of colors of thin plates and of measurements of a wave of light in Familiar Lectures. Asks permission to quote from it.

Suggests experiments with regard to polarization and vaporization, and comets' tails.

In response to JH's comments on JT's explanation of comets says faintness of head and nucleus does not indicate non-existence; eye may not see all. Experiments with polarized light produce 'gorgeous' 'residual blue.'

Corrects misinformation about refraction and dispersion of mercury ethyl and mercury methyl.

Thanks for note [see JT's 1866-5-26] on improvement of the lecturing style of JH's son [Alexander]. JH's son has studied lecture's subject deeply and loves science; JH hopes will be physics professor at a 'considerable institution.'

JT has suggested that JH's son [Alexander] be appointed to position in Royal School of Mines, but colleagues, unwisely, JT thinks, want someone more well-known.

Thanks for paper on action of solar and electric light on vapors, which should give JT further insight into blue color of sky and polarization of skylight. Comments on the latter. JH's son [Alexander] is working hard at Glasgow.

Thinks JT's work on polarization will lead to remarkable discovery. Discusses production of rainbow, parallels to Isaac Newton's explanation of black spot on a soap bubble, and problems in JT's undulatory theory explanation of reflection. In JT's experiments, what are nebulous particles produced by light in gas or vapor?

Continues experiments with carbonic acid and electric light [see JT's 1868-11-30], hoping to 'explode' idea that atmosphere's polarization is due to reflection by air particles.

Thanks for paper verifying JH's prediction that explanation of blue sky color carries with it that of polarization of skylight. Involves ultimate link between chemical and analytical dynamics. Notes that 'neutral points' in sky polarization have yet to be explained; offers tentative explanation based on clues in JT's work.

Thanks for paper on comets. Offers questions, problems to be resolved, particularly on termination of comet.

Surprised that JT cannot obtain heat spots [see JT's 1864-11-14]. Describes glasses and lenses used.

Thanks for lectures on heat motion theory and radiation through earth's atmosphere, and for brochure on 'conformation' of the Alps. Asks about upcoming lecture of JH's son [Alexander].