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Darwin Correspondence Project

From Robert Hunt   24 July 1855

Museum Practl Geology | Jermyn St.

24th July 1855

My dear Sir.

the glasses which I sent you—are not those named in the Researches as the three—effective respectively in accelerating germination—lignification and floriation.1 For the former an intense Cobalt blue glass is required—for the 2nd. a Silver Yellow—and for the 3rd a deep Copper Red. I mean the glasses should be of the fullest tint which those metals will give. If you would write M. Bontemps at Messrs Chance Brothers—Glass Works, Birmingham2 and state the Size—and the character of the glasses you desire to have, I have no doubt he would immediately send them you— You may use my name in writing.

Unfortunately my duties will carry me out of Town this week—and I shall be absent for some time—but any letter sent to the Museum3 will be forwarded to me—and I shall have the greatest pleasure in aiding you to the utmost in your experiments— Since I am not likely to renew them for many years, if ever, I am much pleased to find them taken up by one so well able to investigate this interesting subject

I am | My dear Sir | Yours most truly | Robert Hunt Chs Darwin Esqr


See letter from Robert Hunt, 19 July 1854. The three types of glass are described in Hunt 1854 as: blue glass to encourage germination (pp. 222–3); yellow glass to promote the formation of woody tissue (p. 229); and red glass to stimulate flowering (pp. 236–7).
Georges Bontemps, who had fled from France for political reasons in 1848, initiated the manufacture of specialised optical glass at Robert Lucas and William Chance’s glassworks near Birmingham.
The School of Mines, at which Hunt lectured, was located in the Museum of Practical Geology.


Hunt, Robert. 1854. Researches on light in its chemical relations; embracing a consideration of all the photographic processes. 2d ed. London.


Informs CD which colours of glass accelerate germination, lignification, and floriation; advises CD on obtaining such glass and offers his help in any experiments.

Letter details

Letter no.
Robert Hunt
Charles Robert Darwin
Sent from
Museum of Practical Geology
Source of text
DAR 261.11: 18
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 1730,” accessed on 1 April 2020,

Also published in The Correspondence of Charles Darwin, vol. 5