Sends results of chemical tests on specimens [of salt, see South America, pp. 73–5].
Encloses abstract from Justus Liebig on composition of bones and their ability to withstand decay.
Museum of Economic Geology
I have great pleasure in forwarding the answers to your questions, together with the extract upon bones from Liebig.
You will observe in N
I have tested the salts N
If you will direct me how to send the remainder of the Specimens, they shall be forwarded.
I am | Dear Sir | Your
obedient Servant | Trenham Reeks
C. Darwin Esq
* I believe Carbonate of Lime and Muriate of Soda to have no action upon each other.
1227. Contains plenty of Muriate of Lime 3052. Contains plenty of Muriate of Lime which may account for its dampness.
3048. Is neither Anhydrite nor Sulphate of Lime but consists of about 64 per cent Earthy Matter, with water & Carbonate of Lime, but no Carb
1264. The Crust is Gypsum.
759. Contains a little Sulphate of lime & Magnesia with Mechanical Impurities. I can find nothing in it to account for inefficacy in curing meat.
762. Same as 759.
954. Is chiefly Sulphate of Magnesia.
25. Contains about 7 per cent Animal matter and 8 water.
One hundred parts of dry bones contain from 32 to 33 per cent of dry gelatine; now supposing this to contain the same quantity of nitrogen as animal glue, viz: 5.28 per cent then 100 parts of bones must be considered as equivalent to 250 parts of human urine.
Bones may be preserved unchanged for thousands of years, in dry or even moist Soils,
provided the access of rain is prevented; as is exemplified by the bones of antediluvian
animals found in loam or gypsum, the interior parts being protected by the exterior from
the action of water. But they become warm when reduced to a fine powder, and moistened
bones generate heat and enter into putrefaction; the gelatine which they contain is
decomposed, and its nitrogen converted into carbonate of ammonia and other ammoniacal
salts, which are retained in a great [measure] by the powder itself. Liebig's
Chemistry of Agriculture and Physiology. Page 194.
- f1 825.f1See letter to Trenham Reeks, [before 8 February 1845]. For the use CD made of these replies see Journal of researches 2d ed., pp. 66, 155, 370, later elaborated in South America, pp. 52, 69, 72, 74.
- f2 825.f2Liebig 1842, p. 194. CD possessed an earlier edition of this work (Liebig 1840) in which the cited passage occurs on p. 202. His copy is in the Darwin Library–CUL.
- f3 825.f3Specimen 759 was a salt, from a salina near the town of Patagones (El Carmen), which CD recorded as being particularly inadequate for preserving meat. For Reeks's later analysis see letter from Trenham Reeks, 25 February 1845.
- f4 825.f4CD had apparently requested this reference in connection with his question concerning No. 25 in his letter to Reeks, [before 8 February 1845]. CD cites Reeks and Liebig in his description of the fresh appearance of the fossil bones he found at Banda Oriental (South America, p. 92). The word ‘measure’, which Reeks failed to copy, has been supplied by the editors from Liebig 1842.
- f5 825.f5Gardeners' Chronicle and Agricultural Gazette, no. 6, 8 February 1845, p. 93. Cited by CD in Journal of researches 2d ed., p. 66: ‘those salts answer best for preserving cheese which contain most of the deliquescent chlorides’; i.e., they are not pure sodium chloride.
- f6 825.f6Richard Phillips (see letter from Trenham Reeks, 14 March 1845).
- f7 825.f7Henry Thomas De la Beche, director of the Geological Survey, at whose request Reeks was answering CD's queries (see South America, p. 52).