Ammonium alum in alum-treated wooden artefacts: discovery, origins and consequences

Heritage Science

Table 2 Nitrogen, ammonium and ammonium alum contents of several alum-treated Oseberg wood samples, determined by elemental microanalysis, ATR-FTIR quantification and IC

Sample	Microanalysis	ATR-FTIR		IC
Sample	C/N	NH₄-alum conc. of alum (mol%)	NH₄ estimate (mmol/100 g)	NH₄ (mmol/100 g)
185-F1	4.75
250-2	68.8
279-3a	1.70
410–5	2.22
229-1B-AR	7.09	17 ± 2	33 ± 4	31.8
229-1C-AR	6.29	18 ± 2	35 ± 4	35.4
229-1D-AR	11.1	18 ± 2	32 ± 4	36.0
229-5-AR	11.3	17 ± 2	31 ± 4	23.7
185-1	10.1	14 ± 2	29^a ± 4	25.1^a
185-2	8.56	13 ± 2	27^a ± 4	25.1^a
185-3	9.87	17 ± 2	36^a ± 4	15.1^a
185-4	8.18	11 ± 2	24^a ± 4	38.6^a
185-6	3.71	13 ± 2	27 ± 4
207-powder		84 ± 2	168 ± 4
296-1		8 ± 2	16 ± 4

Values marked with ^a denote quantities per 100 g of aqueous extract, rather than 100 g of total wood sample. The mass of the dried extracts accounted for 85–98% of the mass of the total samples