Grey et al. (1969) have discussed the problems that arise when using the wet oxidation method for the preparation of CO2 from oxalic acid and suggest that, although offering an effective substitute, the dry combustion method also has problems.

This radiocarbon dating laboratory was established to complement the research activities in the field of archaeology and geology in Korea. The benzene liquid scintillation counting method (Noakes, Kim, and Stipp, 1965; Noakes, Kim, and Akers, 1967) is employed in this laboratory because of its compatibility with other dating methods and future possibility in application of this procedure to the biomedical research field. The chemical process for converting carbon from a sample to benzene used by this laboratory is briefly outlined below.

The following list shows the age measurements made at Algiers by the Service des Applications Nucléaires using the C14 method. The laboratory was created in 1965 to answer the increasing demand of the archaeologic research in N Africa, and made its first measurements in 1967. The electronic apparatus employed was completed and calibrated in 1968 and the first tests were performed during the same year. Regular dating-test samples started in June, 1968. The electronic circuits are of commercial origin or made in the C14 Laboratory.

This list contains a selection of dates from analyses carried out during the past few years. Samples are grouped in geologic-palynologic, and archaeologic sections according to main problem. When influence of human activity on pollen diagrams has been observed it has been explicitly indicated. The descriptions and comments have been written in collaboration with collectors and submitters. For the samples from Switzerland, general reference has also been made to Welten (1958a) and to sections on palynology, geology, and archaeology in work edited by the Schweizerische Gesellschaft für Ur- und Frühgeschichte (1968-1970).

Measurements have continued with both the 1 L and 6 L counters. Results are not corrected for C13 fractionation. Errors quoted refer only to the standard deviation calculated from a statistical analysis of sample and background count rates and the Libby half-life of 5570 ± 30 yr. Pretreatment has been continued as described previously (Shotton, Blundell, and Williams, 1969).

This list includes selected dates of archaeologic samples from DDR, Czechoslovakia, Hungary and the Soviet Union made between 1966 and 1969. As in previous lists the major portion of dates are concerned with Neolithic and Early Bronze age period in Middle and SE Europe.

The list given below contains the C14 dates obtained for only archaeologic samples, during 1966 and 1967; for the study of the geologic samples dated during the same period, cf. our previous list Gif-III (Radiocarbon, 1969, v. 11, p. 327-344). The same instruments and techniques have been employed.

This list contains mainly radiocarbon dates for Africa. Some results for samples from the ocean floor and from islands in the Atlantic and Indian oceans, as well as a few series of geophysical samples have also been included. The results are grouped into three categories: geologic, archaeologic, and geophysical, and arranged according to the country of provenance, passing roughly from N to S. Descriptions and comments are based on information supplied by the collectors and submitters and on the publications cited. In several cases insufficient information was available, but since it is improbable that it will be forthcoming, the dates have been included.

The laboratory routinely operates two proportional counters; one 2-L (Dyck and Fyles, 1962) and one 5-L (Dyck et al., 1965). CO2 is used as the counting gas. The 2-L counter is operated mainly at 2 atm. and the 5-L counter mainly at 1 atm. On occasion the 2-L counter is operated at 1 atm. and the 5-L counter at 4 atm. No changes have been made in the CO2 preparation and purification techniques described in previous GSC dating lists (Lowdon et al., 1969; Lowdon and Blake, 1970).

A third radiocarbon counting system has been established in the Chemistry Department, University of Glasgow, since April, 1968. Operating conditions for the previous systems have remained essentially as described by Baxter et al. (1969).

The following list presents results obtained during 1968-69 on a series of samples chosen to investigate temporal variations of C14 concentrations in the atmosphere during the past century. Together with data presented previously (Radiocarbon, 1969, v. 11, p. 45-52) they constitute a study of annual variations of C14 activities at N temperate latitudes.

The following date list includes samples processed by the Illinois State Geological Survey Radiocarbon Dating Laboratory from September 1968 through November 1969. Detailed descriptions of sample methods are published elsewhere (Kim and Ruch, 1969; Kim, Ruch, and Kempton, 1969).

The laboratory has been operating more than five years, supported entirely from Venezuelan government funds. Approximately 530 samples have been dated to the end of 1969. Of these, 40% are archaeologic specimens, the majority (141 samples) from Venezuela. Materials from most other countries of Latin America have been processed. The rest of the samples are from research programs of the Radiocarbon Laboratory itself. Thirty per cent of the total are measurements on carbonate species extracted from Venezuelan ground water aquifers.

Measurements reported in this paper were obtained with the 4.5 L and 3 L CO2 counters, details of which were given earlier (Radiocarbon, v. 11, p. 423). The automatic data recording system built in 1968 (Hänsel, 1968) is now operating for both counting apparatus. For each one the counts of the guard counters ring (A counts), the total counts of the C14 counter (B counts), the coincidences of central and guard ring counter (AB counts), and the anticoincidences (ĀB counts) are tape punched every 100th minute. By an ALGOL program, all counts are checked first for large disturbances. Secondly, equation B = AB + ĀB must hold (as an integral check for proper operation of logical circuitry and the data recording system) and finally statistical compatibility is examined before age and other data for the actual counting apparatus are computed. This detailed check of counting rates by computer has proved to be very efficient to yield reliable long-term measurements.

The C14 measurements reported here were made in this laboratory between October 1968 and October 1969.

The C14 dates given below have been obtained by counting CH4 at 3 atm pressure in a 0.6 L stainless steel counter. Details of procedure are given in the previous lists. Dates are reported in terms of the Libby half-life, 5570 ± 30 years; the errors quoted are based on the standard deviations in counting rate of samples and standards.

The C14 dates given below are a continuation of the work presented in our previous list (Radiocarbon, 1969, v. 11, p. 451-462), and results obtained mainly during 1969 are described. A new 3.3 L copper counter was put into routine operation besides the 2.7 L stainless steel counter employed heretofore, yielding background counting rates of 8.5 and 5.5 cpm, respectively, when filled with dead CO2 at ca. 1.8 atm.

This date list includes those series of samples completed in this laboratory as of November 1969. The b.p. ages are based upon a.d. 1950, and are calculated with a half-life value of 5568 yr. All samples were counted at least twice for periods of not less than 1000 minutes each. Errors quoted are derived from measurement of samples, background, and modern-age calibration, but do not include any half-life error. All samples were pretreated with 3N HCl, and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic contaminants.

The University of Cambridge Radiocarbon Dating Laboratory has been completely rebuilt and modernized, incorporating new techniques developed here for the various stages of measurements. Sample radioactivity is measured in gas proportional counters after conversion to highly purified CO2. Four counters are mounted within a single anticoincidence shield consisting of plastic scintillation material. This is surrounded by a graded cosmic ray shield of low radioactive steel, boron loaded wax, and finally, about 16 tons of ancient low radioactive lead blocks. The electronics are all solid state devices except for the stabilized high voltage supplies.

This list includes age measurements carried out from December 1968 to October 1969. Archaeologic samples are from Italian and Swat (W Pakistan) territories. All geologic samples come from Italian territory. Chemical techniques remain the same (Bella and Cortesi, 1960; Alessio, Bella, and Cortesi, 1964).