Title and Abstract in English, French and German, while paper is in English. The use of manganese as a colorant in ancient glasses has long been recognized and the recent X-ray diffraction measurements of Turner and Rooksby have established that compounds of antimony were used extensively as opacifiers in such glasses. The analysis at Brookhaven National Laboratory of some three hundred ancient western glasses of the second millennium B.C. through the first millennium A.D., of which more than two hundred contained either or both of these elements in sufficiently great concentrations to indicate deliberate additions, not only has provided confirmation of these observation but also evidence that both of these elements were used extensively to counteract discoloration due to iron in glasses intended to be clear and colorless. As is well known in the case of manganese the different behavior of antimony in different glasses appears to depend upon its chemical valence. The technique of decolorizing glass by means of antimony was introduced at about the seventh century B.C. and the similar use of manganese became widespread during the first century A.D. In the following period through the fourth century the alternate or combined use of these decolorants forms an …

Several sources of error often involved in radio-gas chromatography are delineated and proposals for improved techniques are made. Remarkable changes of flow rate (and hence efficiency changes of a continuous flow counter), which occur after the injection of large gas samples, have been studied as functions of the variables involved. A new flow meter is described, which allows a continuous recording of the flow rate, independent of the viscosity of the gas. When a mass peak emerges from a gas chromatographic column, a relatively large change in the flow rate is likely to occur. The error involved is particularly serious in the cases when the radioactivity of the effluent gases is determined with a flow counter, whose efficiency depends upon the flow rate. The simple and highly precise flow meter described allows one to measure and therefore correct for the flow changes. An example is given of a radio-gas chromatographic analysis of mixtures C¹⁴- and C¹¹-labeled hydrocarbon obtained by nuclear recoil. A convenient and precise evaluation of the radioactivity in the peak of the gas chromatographic effluent digital printout system is described. An application of the improved radio-gas chromatographic technique is given for the analysis of C¹⁴- and C¹¹- recoil …