The radiocarbon dating laboratory in the Institute of Marine Science at the University of Alaska was established in the fall of 1968 and became operational a year later. Most of the samples examined have been from Alaska and consist largely of wood and peat.

The following list consists entirely of dates for archaeologic samples from the British Isles measured since about mid-1970 up to June 1974*. The dates were obtained by liquid scintillation counting of benzene using a Model 3315 Packard Tricarb Liquid Scintillation Spectrometer. In general, procedures are as described in the previous date list (R, 1971, v 13, p 157; see also Burleigh, 1972). However, data processing was improved by means of a real-time link with a Hewlett Packard 2100A computer having 32K of core, which accepts readings from the counter at the end of each individual counting period. The computer monitors the accumulated sample counts and reports when the statistical error terms of these have reached previously chosen limits; final dates are then obtained on supplying the appropriate benzene sample weights and isotopic fractionation values. The system maintains a permanent record of all the data obtained from measurement of samples and reference standards and gives warning of any serious changes in counter performance. A full description of the capabilities of this system is given elsewhere (Hall and Hewson, in press). Finally, improvements were made to the bomb used for initial combustion of sample materials (Burleigh, 1974) and a new, stainless-steel, lithium reaction furnace (similar to that described by Polach and Stipp, 1967) was recently installed.

The Dalhousie University Radiocarbon Dating Laboratory was established in 1972, utilizing equipment and procedures formerly in use at Ohio Wesleyan University, Delaware, Ohio. The laboratory is located on the third floor of the 8-story Life Sciences Center at Dalhousie University. Sample preparation includes leaching with dilute alkali and acid, followed by pyrolysis in a stream of N2 at 500°C. Operating procedures remain essentially the same, utilizing reduction of acid or combustion generated CO2 to the counting gas, methane, over Ruthenium catalyst at 500°C. The flow reactor formerly used has been replaced by an in-line static reactor. Following gas purification and one month product gas storage to permit decay of Radon, samples are counted at 50 to 152cm pressure in either of 2 500ml detectors, or a 2L detector.

The first natural 14C measurements in Poland were made, using CO2 + CS2 G M counter as early as 1953 (Mościcki, 1953), but continuous operation was not possible until 1971. Following Poznań Toruń (Mościcki, 1958; 1961) and Gdańsk (Mościcki and Zastawny, 1962a), where the first long series of 14C measurements were made (Mościcki et al, 1967), an actively operating radiocarbon dating laboratory was installed at Gliwice in 1971.

This list includes most of the samples measured during 1974 and most of those measured previously but not published in the preceding date list (R, 1975, v 17, p 4–34.)

As the Radiocarbon Lab of the Tata Institute, Bombay, has now been shifted to the Physical Research Laboratory (PRL), Ahmedabad, our new date lists will be termed as above and the samples will be given PRL numbers instead of the former TF. All the pending TF samples were given new PRL numbers.

This list describes samples dated in this laboratory between November 1972 and December 1974.

This list comprises age measurements carried out from 1973 to 1974 In dating the samples reported here as well as in calculating their ages, the same equipment and methods were used as previously described (R, 19/3, v 15, p 586–591; 1974, v 16, p 388–394).

The following list of dates are selected from geologic and archaeologic samples measured in early 1975. The technique employed is liquid scintillation counting of wholly synthesized benzene as described by Noakes et al (1965) and discussed in R, v 16, p 402–408. Errors are reported as one standard deviation.

Procedures and equipment of the laboratory have been described in previous date lists. Lake cores and marls are treated with acid only, wood, charcoal, and peat samples with dilute NaOH and dilute H3PO4 (unless indicated otherwise) before conversion to methane which is used as counting gas.

This list of radiocarbon age measurements is for the period 1972–1974. Most of the samples are of archaeologic interest. The pretreatments of samples used are basically those described by Ralph and Michael (1971). All samples were converted to methane using the method developed by Fairhall, Schell, and Takashima (1961) and counted in .5L counting tubes at 2 to 4atm of pressure. The WSU Radiocarbon Laboratory has been relocated to the basement of Dana Hall (three stories) and additional shielding has been added. The backgrounds of the counting tubes are .90 counts/min and have an atmospheric pressure dependence of –.035 counts/min/cm Hg.