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Darwin Correspondence Project

From A. W. von Hofmann to Edward Cresy   27 October 1860

R. College of Chemistry

Oct. 27. 1860.

My dear Sir

I enclose you the book on poison from which my statement about arsenic was taken. Taylor explains his opinion so well that I need not add a word.1

I have made a few experiments with Iodine and find that 0.001 milligramme of iodine dissolved in 1 Gramme of water is scarcely indicated by the starch test,—but that 0.002 Milligrammes dissolved in 2 Grammes of Water is easily distinguished by that test.


Hoping that this information will prove useful | Yours very truly | A W Hofmann

E. Cresy Esq


See letter from A. W. von Hofmann to Edward Cresy, 13 October 1860. CD had questioned the system of measurement used by Hofmann (letter to Edward Cresy, 14 October [1860]). Hofmann refers to Taylor 1848. Hofmann’s letter was sent to CD by Cresy enclosed with a letter of his own (see letter from Edward Cresy, 30 October 1860).


Taylor, Alfred Swaine. 1848. On poisons in relation to medical jurisprudence and medicine. London.


Is enclosing Alfred Swaine Taylor’s book On poisons (1848). Reports on his own experiment with the starch test in dissolving iodine in different measures of water.

Letter details

Letter no.
August Wilhelm von Hofmann
Edward Cresy, Jr
Source of text
DAR 58.1: 5
Physical description
ALS 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 2966A,” accessed on 21 March 2023,

Also published in The Correspondence of Charles Darwin, vol. 8