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Darwin Correspondence Project

To J. H. Gilbert   [before 9 March 1876]1

Down | Beckenham | Kent

My dear Sir

I thank you most cordially for the great trouble which you have taken in writing to me at such length.2 Your letter is of the greatest value to my son3 & my self & we shall at once order the necessary salts at Messrs Griffin & begin preparing the soil.4

May I ask you two other questions which you could answer very briefly?

(1) Can you tell me to what point the soil should be burnt? I presume that clay burnt to the same amount as bricks (which would be equivalent to powdered brick) could not be properly purified by washing? We thought of making a rough gridiron of iron bars raised from the ground, so as to roast a layer of clay spread on it, by lighting a wood & coal fire under it. Do you think that this method would answer? we have the same kind of soil you mention in the Phil Trans ie clay & flints on chalk5

(2) Would it be advisable to wash the soil once with dilute acid in order to insure its freedom from alkali?

Pray thank Mr Lawes for his very kind message.6

I am sorry to say that I am not strong enough to accept it, but my son would very much like to inspect your plots in May or June. He has hardly sufficient Botanical knowledge; but an examination of your plots would be highly interesting & instructive to him

With very sincere thanks | I am dear Sir | Yours very faithfully | Ch. Darwin


The date is established by the relationship between this letter and the letter from J. H. Gilbert, 9 March 1876.
Francis Darwin.
In his letter of 4 March 1876, Gilbert had suggested that CD obtain the salts for his experiments with soil containing no nutrients from John Joseph Griffin & Sons, 22 Garrick Street, Covent Garden.
In Lawes et al. 1861, p. 471, a similar method of burning the soil is described; it is stated: ‘The soil selected for the preparation of the matrix was a somewhat heavy one (clayey), resting upon chalk, and interspersed with flints.’ Phil Trans: Philosophical Transactions of the Royal Society of London.
Gilbert and John Bennet Lawes had invited CD and his son Francis to visit the Rothamsted Experimental Station in Harpenden, Hertfordshire; see letter from J. H. Gilbert, 4 March 1876. See also letter from J. H. Gilbert to Francis Darwin, 10 June 1876 and n. 3.


Thanks for advice concerning preparation of soil for experiments. Will order the salts. Asks about burning soil or washing it with acid.

Thanks for invitation. His son [Francis] would like to inspect JHG’s plots.

Letter details

Letter no.
Charles Robert Darwin
Joseph Henry Gilbert
Sent from
Source of text
Rothamsted Research (GIL13)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10376,” accessed on 5 August 2020,

Also published in The Correspondence of Charles Darwin, vol. 24