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
2
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).
3
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).

Please cite as “DCP-LETT-9671,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9671