skip to content

Darwin Correspondence Project

From David Forbes   1 March 1872

11, York Place, | Portman Square, | London. W.

1 March 1872

Dear Mr Darwin

As you know that I rather pride myself on being systematic—I was annoyed today that I could not at once lay my hands on the analyses of chalk, I found them the moment you left1—the difficulty in doing so before being because I had entered them under the head of investigations of the Atlantic mud2

I enclose herewith the results of 2 analyses which you can take as representatives only to show the components of the true chalk which contains the flints—and of the most impure or grey chalk (chalk marl)—lowest in the series

Yours very truly | David Forbes

White chalk– with flints

Shoreham

Carbonate of Lime – 98.40

— of Magnesia 0.08

Insoluble (silicious rock debris) 1.10

Alumina(with Phosporic acid 0.42

100.00 Grey chalk. beds resting on greensand

level of low water   Folkestone

Carbonate of lime 94.09

— of Magnesium 0.31

Insoluble (rock debris) 3.61

Phosphoric acid traces Sea infiltration Chloride of sodium 1.29

Water 0.70

100.00

CD annotations

Top of letter: ‘Worms’3red crayon

Footnotes

Forbes analysed chalk samples in order to compare them with samples of Atlantic mud collected on the Lightning and Porcupine expeditions (see Quarterly Journal of the Geological Society 27 (1871): xlviii–xlix n., and Thomson 1873, pp. 467 ff.).
CD cited the results of Forbes’s analysis of chalk in Earthworms, pp. 299–300.

Summary

Sends information on composition of chalk at Shoreham and Folkestone.

Letter details

Letter no.
DCP-LETT-8233
From
David Forbes
To
Charles Robert Darwin
Sent from
London, York Place, 11
Source of text
DAR 164: 149
Physical description
2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 8233,” accessed on 19 June 2019, http://www.darwinproject.ac.uk/DCP-LETT-8233

Also published in The Correspondence of Charles Darwin, vol. 20

letter