skip to content

Darwin Correspondence Project

From Edward Frankland   [before 6 June 1876]1

—— Burnt Soil ——
Moisture at 100o 0.50 per cent
Loss on Ignition 1.20
Silica 89.09
Ferric Oxide 3.88
Alumina 3.41
Lime 0.84
Magnesia 0.49
Potash 0.15
Soda 0.04
Phosphoric Anhydride 0.092
Natural Soil
Moisture at 100o 2.22 per cent
Loss on ignition 4.26
Silica 77.72
Ferric oxide 5.52
Alumina 8.79
Lime 0.48
Magnesia 0.51
Potash 0.33
Soda 0.26
Phosphoric Anhydride 0.04
Sulphuric do traces


The date is established by the relationship between this letter and the letter to Edward Frankland, 6 June [1876].
Phosphoric anhydride is more commonly known today as phosphorus pentoxide; alumina is synthetically produced aluminum oxide. ‘Loss on ignition’ is a test used in analytical chemistry in which a sample is heated and then weighed until the mass is stable; for organic matter the temperature is high enough to burn organic matter but not so high as to decompose carbonates.
CD had sent Frankland samples of burnt and unburnt soils to analyse; see letter to Edward Frankland, [before 6 June 1876].


Sends analysis of burnt and unburnt samples.

Letter details

Letter no.
Edward Frankland
Charles Robert Darwin
Source of text
The John Rylands Library, The University of Manchester
Physical description
incomplete 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 10533F,” accessed on 3 August 2020,

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