Chemical Examination of the Piltdown
Nature December 12, 1953
K. P. Oakley and J. S. Weiner
[1110} In the report 1 on the main results of our re-examination of the Piltdown material, we gave reasons for regarding the chromate staining of the mandible as indicating a deliberate attempt to match a modern bone with the mineralized cranial fragments. The actual composition of this bone (3-9 per cent nitrogen, less than 0-03 per cent fluorine) suffices to prove its modernity; but the chromate staining, combined with the artificially abraded appearance of the molars, indicates that it is not only modern but also fraudulent.
In case there is any lingering doubt that the Piltdown finds are in part fraudulent, we think that one other fact now bought to light should be published immediately. Suspecting that some of the so-called implements' 2 reported from the site might have been 'doctored', we asked Mr. E. T. Hall, of the Clarendon Laboratory, Oxford, to test the composition of their surface stains by means of his X-ray spectrographic method of analysis. He has reported to us that the stains on these flints are entirely ferruginous, with one notable exception. The triangular flint (Reg. No. E.606) recovered in situ from the layer immediately overlying the skull horizon 3 is chromate stained. When this stain is removed in acid the flint appears greyish-white. It is indistinguishable from a mechanically broken piece of flint such as one might encounter on the surface of any ploughed field in 'Chalk-land'.
Whereas a bone might have been dipped in a solution of potassium dichromate with the sole purpose of trying to harden it, a flint would only have been treated in that way by a forger requiring it to be of a certain colour.
xvi, fig. 2 (1913)