The following list comprises results obtained during 1971 from both the 1 L and 6 L proportional gas counters at pressures of 1 to 3 atm of methane. Age calculations are based on 95% activity of NBS oxalic acid standard and computed from the Libby half-life of 5570 ± 30 yr. Background samples are synthesized from Welsh anthracite. Errors quoted refer only to the standard deviation (1σ) calculated from a statistical analysis of sample, background, and standard count rates. Recently a Micromass 6 mass spectrometer was installed in the Radiocarbon Dating Laboratory which will enable C13 measurements on future samples. Pretreatment is continued as described previously (R., 1969, v. 11, p. 263) but in cases where sample size was insufficient for full pretreatment, details are described.

Radiocarbon measurements, mainly on soil and water samples are being continued. Benzene samples are prepared as described earlier (Scharpenseel and Pietig, 1969). By adding another counting unit, the lab. now uses 3 liquid scintillation spectrometers and 4 benzene synthesis lines.

This list continues Gakushuin VII (R., 1969, v. 11, p. 295–362); the same instruments and techniques were employed. Age calculations are based on the Libby half-life of C14, 5570 ± 30 years, and the modern activity given by 95% of the activity of NBS oxalic acid standard. Errors quoted are the standard deviation obtained from the number of counts only. When observed activity is less than 2σ above background, infinite date is given with a limit corresponding to the activity of 3σ. For shell samples, dates are computed without any correction for environmental and biological isotopic fractionation. The description and comments are essentially those of the submitters.

The radiocarbon dating laboratory of the University of Hawaii was established with joint support of the Hawaii Institute of Geophysics, the Water Resources Research Center, the Department of Chemistry, and the Graduate Division. The laboratory is located in the Hawaii Institute of Geophysics, on the ground floor of a four-story concrete building, and contains two separate radiocarbon counting systems.

This date list includes all samples processed from December 1970 through November 1971 at the Illinois State Geological Survey Radiocarbon Dating Laboratory. The benzene liquid scintillation method of Noakes, Kim, and Stipp (1965), and Noakes, Kim, and Akers (1967) was used. A new benzene synthesis system has been completed, and several changes in the sample preparation procedure have been made since the last date list report (Coleman, 1972). A brief summary of the benzene synthesis and sample pretreatment techniques used to determine the dates reported here follows.

The following list comprises a selected number of measurements made on archaeologic samples from 1959 to December 1971. Measurements of geologic samples will be given in a later date list. A survey of the radiocarbon chronology for the Danish Mesolithic and Neolithic, ensuing from these and previously published dates from the laboratory, has recently been compiled (Tauber, 1972).

This list contains data obtained during 1971. Unless otherwise stated, all organic samples or organic fractions are carefully washed with dil. HCl and dil. NaOH to remove all carbonates. Age calculations are based on 95% of NBS oxalic acid standard activity with modern value A.D. 1950. Results are calculated using the Libby half-life and are given in the B.P. scale. Also ages of shells are calculated with the NBS oxalic acid standard. Ages are not corrected for δC13 variations. Errors correspond to Iσ variation of sample net counting rate including statistics of modern standard and background. Sample activities, if given in per cent refer to 0.95 NBS oxalic acid standard activity.

The following list comprises selected measurements made in the Louvain 14C Dating Laboratory with the 0.6 L CH4 proportional counter. Details of procedure are given in previous lists. Dates are reported in terms of the Libby half-life, 5570 ± 30 years and quoted with 1σ experimental error.

The present list includes most of the samples measured since the establishment of the laboratory in 1965 and not yet published in the two previous dates lists.

The measurements presented in this paper were carried out at the University Radiocarbon Dating Research Laboratory during the second half of 1971 using carbon dioxide counting. The counting equipment used was substantially that described by Switsur, Hall, and West (1970). Oxidation of samples of sufficiently high carbon content was performed in a stainless steel high pressure combustion bomb, developed at this laboratory, otherwise by ‘wet’ oxidation using acidified permanganate solutions for lake mud and samples of low organic content.

This list includes age measurements made from November 1970 to December 1971. All archaeologic and geologic samples come from Italian territory. Laboratory equipment, largely unchanged but expanded and technically improved, was previously described (Alessio et al., 1970a). Charcoal and wood samples underwent standard pretreatment by boiling with 5 to 10% HCl; α-labeled samples were given additional leaching with 6% NH4OH or 0.2N NaOH.

This list contains results obtained since July 1970. They are mainly hydrologic and geologic samples prepared and counted as described in our previous date list, (Carmi et al., 1971). The coordinate system used to describe sampling locations is the local one.

The radiocarbon dating laboratory at Rice University first became operative in the fall of 1970. A workable technique has been developed although operations are still in a state of flux. The benzene liquid scintillation counting method is used, the benzene being prepared as outlined by Noakes, Kim, and Akers (1967) with the following modifications. The CO2 is further purified prior to storage and measuring by passing it through 3 gas bubblers containing potassium permanganate solution, silver nitrate solution, and a sulfuric acid-sodium dichromate solution (S. Valastro, pers. commun., 1970). Since no C12 C13 analyses are available at present, to insure a complete reaction, both the CO2 generation and the C2H2 generation are continued for ½ hr after all visible signs of reaction have disappeared.

This series reports some of the measurements made since publication of the previous list. Equipment and methods remain as described in Saskatchewan II (R., 1960, v. 2, p. 73). The laboratory operates now commercially, administered by the Saskatchewan Research Council under the direction of A. A. Rutherford.

The dating equipment and operating conditions remain essentially as previously described. Samples in this list were counted at filling pressures equivalent to either 152 or 380 cm Hg at 20°C. Pretreatments are as given in previous lists unless otherwise specified. All wood samples were treated with sodium chlorite and dilute HCl to leave a cellulose-rich residue. Pine wood was in some cases extracted with petroleum spirit in a Soxhlet apparatus before this treatment, to remove resins.

Radiocarbon dates obtained since December, 1970, are summarized here. Procedures and equipment have been described previously (R., 1966, v. 8, p. 522). Wood, charcoal, and peat samples are pretreated with dilute NaOH and dilute H3PO4 before conversion to the counting gas, methane; marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4.