Yale Natural Radiocarbon Measurements V

The following list of dates, measured since the publication of Yale IV, includes a few repetitions of published dates, noted as such by the addition of bis to their number. One of these (Y-140 bis ) was a new preparation of CO 2 from a sample previously measured as acetylene; the others are rechecks of repurified CO 2 , repeated because instrumental difficulties plagued our laboratory throughout the year beginning in September 1958 and might have affected some dates published in Yale IV. No important differences were found, however. Several measurements of geochemical interest, on lake water and other lacustrine materials for which C 13 analyses have been reported (Oana and Deevey, 1960), are not included here but will form the subject of a separate paper.