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Darwin Correspondence Project

To Edward Frankland   23 September 1873

Down, | Beckenham, Kent.

Sep 23. 1873

My dear Sir

Many thanks for your renewed kindness. I have written to Dr Moore to ask him to prepare some fibrin for me & to test its purity from Hydro chloric acid & all salts. As he has been accustomed to prepare animal compounds, I shd think he might be quite trusted. I told him that you were going to test for the acid.1

I procured doubly distilled water from Messrs Hopkins & Williams.2 It is not free from particles when viewed in a strong light, & when evaporated, leaves a little residue. I put a drop on a glass plate & added a little weak nitrate of silver, & I could see no trace of a cloud, so I hope it is sufficiently pure.3

As soon as I get the fibrin I will set to work with the leaves.

Yours sincerely obliged | Ch. Darwin


See letter from Edward Frankland, 22 September 1873. CD’s letter to Samuel William Moore has not been found, but he had already received casein from Moore (see letter to Edward Frankland, 21 September [1873]).
Hopkin & Williams was a firm of manufacturing chemists with premises at 10 New Cavendish Street, London (Post Office London directory 1872).
Silver nitrate reacts with chlorides in water to form a cloudy white precipitate (silver chloride).


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.


Will follow EF’s suggestions as to securing purity of fibrin.

Letter details

Letter no.
Charles Robert Darwin
Edward Frankland
Sent from
Source of text
The John Rylands Library, The University of Manchester
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9064A,” accessed on 16 October 2021,

Also published in The Correspondence of Charles Darwin, vol. 21