Published online by Cambridge University Press: 18 July 2016
For determining age scintillation variant was used. Measurement of a large quantity of benzol [benzene] permitted reaching a limit of 62,000 yr without isotope enrichment. Precautions against contamination of the samples with contemporary carbon and tritium were taken in laboratory handling. Dating began only after it had been established that contamination had not taken place during chemical treatment. Benzol which displayed no radioactivity was synthesized from anthracite. Special measures were taken to remove humic acids from the sample by boiling the powdered sample for three days with three fresh lots of 2% solution of NaOH (Arslanov et al., 1966a, p. 134).