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Darwin Correspondence Project

From Edward Frankland   9 October 1874

Royal College of Chemistry | South Kensington Museum

9th. October 1874.

My dear Mr. Darwin

I am quite ashamed of myself for not having answered your letters,1 but the fact is that they followed me about Europe for several weeks before I received them, & then I had no books to refer to.

The phosphate of ammonia which you obtained from Messrs Hopkin & Williams would be, I imagine, the Diammonic Phosphate the sp. gr. of which is 1.678.2

The nitrogenous substances produced during the putrefaction of animal matters have been little if at all investigated & I am unaware of any material which occupies such a relation as urea to the original substance. The decay of flesh skin &c. in contact with air & water is attended with the rapid production of nitrate & carbonate of ammonia.3

I fear this information comes too late to be of any use. I have just returned to England after an absence of 3 months.

Yours very sincerely | E. Frankland

CD annotations

2.1 The phosphate of ammonia] scored blue crayon
2.2 the Diammonic … 1.678.] double scored blue crayon
3.3 The decay … ammonia. 3.5] double scored blue crayon
3.4 rapid] underl blue crayon


See letters to Edward Frankland, 22 July 1874 and 31 August 1874.
CD had asked about the specific gravity of different forms of phosphate of ammonia in his letter of 22 July 1874; he discusses it in Insectivorous plants, p. 173 n. Hopkin and Williams were manufacturers of laboratory and photographic chemicals with offices at 16 Cross Street, London, and a factory in Wandsworth, Surrey (Post Office London directory 1875).
In his letter to Edward Frankland, 31 August 1874, CD asked about the products produced ‘towards the close of the putrefaction of flesh, skin &c’ for his experiments on Utricularia (bladderwort).


Insectivorous plants. By Charles Darwin. London: John Murray. 1875.

Post Office London directory: Post-Office annual directory. … A list of the principal merchants, traders of eminence, &c. in the cities of London and Westminster, the borough of Southwark, and parts adjacent … general and special information relating to the Post Office. Post Office London directory. London: His Majesty’s Postmaster-General [and others]. 1802–1967.


Sends information CD requested on phosphate of ammonia and on nitrogenous substances produced during putrefaction of animal matter.

Letter details

Letter no.
Edward Frankland
Charles Robert Darwin
Sent from
R. Coll. Chem.
Source of text
DAR 58.1: 97–8
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 9671,” accessed on 25 February 2021,

Also published in The Correspondence of Charles Darwin, vol. 22