All samples processed from February 1973 through January 1974 at the Illinois State Geological Survey Radiocarbon Dating Laboratory are reported here. The benzene liquid scintillation technique was used. Laboratory procedures used were the same as those previously reported by Coleman (1973, 1974).

This list includes most of the samples measured from June 1972 to December 1973 and some other results as yet unpublished.

This list includes the second group of age measurements made from September 1972 to July 1974 using the benzene scintillation method. All archaeologic and geologic samples come from Italian territory. Chemical apparatus for benzene synthesis and the liquid scintillation spectrometer are unchanged (Alessio et al, 1970a, 1973). Charcoal and wood samples underwent standard pretreatment by boiling with 5 to 10% HCl; α-labeled samples were given additional leaching with .2N NaOH. The counting rate of approx half the samples was corrected based on the 13C/12C ratio, mass-spectrometrically measured on CO2 obtained in combustion line set up after Broecker et al (1959), according to previously described procedure (Alessio et al, 1969).

A radiocarbon facility has been installed at the University of California, Riverside (UCR) to support interdisciplinary studies including archaeologic, archaeometric, geophysical, and geologic research. The laboratory was built between 1970 and 1973. Initially, a sample pretreatment and combustion system designed for a proportional CO2 counting system was installed. It was designed after concepts developed at the University of California Los Angeles (UCLA) and New Zealand (Institute of Nuclear Sciences) Laboratories, and began processing samples in November 1972.

The following list of dates contains all measurements made during 1973, ie, since our last list (R, 1973, v 15, p 451–468). We have installed this year a Nuclear Enterprises NIM system to be used with our 2.5L Oeschger-type proportional counter (Philips), in addition to our 6L and 1L proportional counters which have worked consistently with Beckman Lowbeta electronics. The Philips counter has been calibrated relative to the Beckman electronics and we are now calibrating it relative to the NIM system.

The Dublin radiocarbon dating laboratory was operational in 1958 to 1960 and the scintillation counter system used at that time has previously been described (Delaney and McAulay, 1959). The system is now operational again and has been modified to date samples after conversion to benzene. The electronic equipment differs from that previously used only insofar as more compact and drift-free transistorized units are now employed. With these modifications, considerable improvements in sensitivity and accuracy are obtained. 5ml benzene, diluted with a commercial toluene based scintillant is used in a 12.5ml silica cell for the detection of 14C disintegrations. The background count-rate varies inversely with the barometric pressure (ca 2.6% cm–1Hg). The background is ca 3.4cpm, and the detection efficiency is ca 60% and excludes the tritium spectrum.

The SMU Radiocarbon Laboratory is operated by the Department of Geological Sciences within the Institute for the Study of Earth and Man. One laboratory room contains the benzene synthesis system where samples are pretreated and converted to CO2 in a standard way and gas is purified after the procedures of Broecker (1957) by passage through hot CuO, 10% AgNO3 solution, chromic acid, hot copper, and P2O5 via cryogenic pumping with liquid nitrogen. Purified CO2 is then converted to Li2C2 which is hydrolized to C2H2 and converted to C6H6 catalytically following the procedures of Noakes et al (1966). Carbon dioxide and benzene yields are routinely in excess of 90% in both cases.

This list comprises age measurements carried out from October 1972 to July 1973. Samples dated are all of archaeologic interest and come from Italian territory. Pretreatment of samples, production of purest CO2 and counting techniques have been described elsewhere (Azzi, 1972; Azzi et al, 1973).

The Organisation of Egyptian Antiquities believes that Egypt should play an important role in current international research in the field of radiocarbon dating of archaeologic samples. Thus, such a laboratory was established within the Center of Research and Conservation of Antiquities, CRCA, Cairo.

The Low-level Measurements Laboratory at AERE, Harwell was set up some years ago principally to measure natural levels of tritium in water for hydrologic applications. The measurement of 14C in groundwater carbonates was a logical development from this work. In the period 1971–73 the measurement system has been extended to include archaeologic samples and this is the first list of dates for samples submitted during that period.

On two previous occasions we have published lists of 14C results of precisely dated wood samples in Radiocarbon as per mil deviations (R, 1965, v 7, p 179–186; R, 1969, v 11, no. 2, p 469–481). We have also published a list of 14C dates, consolidating all dated wood samples processed in our lab to July 1969 (Ralph and Michael, 1970).

Radiocarbon measurements, mainly on soil and water samples are being continued. Benzene samples are prepared as described earlier (Scharpenseel and Pietig, 1969; 1970). Radioactivity is measured in a single quartz vial, and also with 13 specially manufactured, low background Teflon/Duraluminium vials, similar to the system described by Polach (1971, pers commun).

This date list was compiled by the Institute of Geological Sciences (UK) incorporating data supplied under contract by E Welin, Radioactive Dating Laboratory, Stockholm. Unless otherwise stated, age figures are in 14C years before ad 1950. The half-life of 14C is taken as 5568 years and the error, based on counting statistics of sample, background, and modern, is given as one standard deviation. Correction for 13C/12C fractionation has been made.