THE TWO PHYSICAL DETERMINATIONS SHOW GENERALLY HIGH REPRODUCIBILITY AND PRECISION AND ARE RELATIVELY INEXPENSIVE AND RAPID. HOWEVER, WEAKNESSES OF THESE TWO TECHNIQUES INCLUDE THE MUTUALLY DEPENDENT PROPERTIES OF DENSITY AND REFRACTIVE INDEX AND THE NARROWNESS OF THEIR DISCRIMINATIVE RANGE. THE EVIDENTIAL VALUE OF DISCRIMINATION BETWEEN GLASS SAMPLES CAN BE SIGNIFICANTLY INCREASED BY APPLICATION OF CHEMICAL ANALYSES. ENERGY DISPERSIVE ANALYSIS IN A SCANNING ELECTRON MICROSCOPE AND EMISSION SPECTOGRAPHY ARE TWO OF A NUMBER OF CHEMICAL ANALYSES WHICH CAN BE USED TO DIFFERENTIATE BASIC COMPOSITION AND TRACE ELEMENTS ARISING FROM RAW MATERIALS AND MANUFACTURING PROCESSES IN GLASS SAMPLES. AN ANALYSIS OF 40 WINDOW GLASS SAMPLES WAS UNDERTAKEN USING THESE FOUR TECHNIQUES. REFRACTIVE INDEX WAS MEASURED BY A METTLER HOT-STAGE AND THE BECKE LINE TECHNIQUE. CLOVE OIL AND MS 710 SILICONE OIL WERE USED AS IMMERSION LIQUIDS. THREE READINGS WERE TAKEN ON EACH SAMPLE. ARCHIMEDES' PRINCIPLE WAS USED TO DETERMINE ABSOLUTE VALUES FOR DENSITIES. ENERGY DISPERSIVE X-RAY ANALYSIS WAS CARRIED OUT WITH JSM-35 SCANNING ELECTRON MICROSCOPE EQUIPPED WITH A PGT-1000 X-RAY ANALYZER. THE ACCELERATING VOLTAGE WAS 25KV. SAMPLES WERE WASHED WITH DISTILLED WATER AND ACETONE, CRUSHED, AND FRAGMENTS OF A MAXIMUM SIZE OF 1 MM IN ANY DIRECTION WERE MOUNTED ON CARBON BLOCK. IT IS OF PARTICULAR IMPORTANCE THAT THE TILTING ANGLE AND THE POSITIONS OF THE X-RAY DETECTOR AND THE SAMPLES BE KEPT CONSTANT. ANALYSIS OF TRACE ELEMENT COMPOSITION BY EMISSION SPECTOGRAPHY INVOLVED ANALYSIS OF ABOUT 2 MG GROUND GLASS BLENDED WITH GRAPHITE POWDER ON A 3.5-M EMISSION SPECTOGRAPH WITH A RESOLUTION OF 75 600. IN GENERAL ONLY SAMPLES WHICH COULD NOT BE DISTINGUISHED BY ENERGY DISPERSIVE X-RAY ANALYSIS WERE SUBJECTED TO THIS FURTHER ANALYSIS. DENSITIES OF ELEMENTAL LINES WERE MEASURED BY A MINICOMPUTER AND PRINTER ATTACHED TO A COMPARATOR. WAVELENGTHS OF ELEMENTAL LINES AND COMPARATIVE AND ANALYTICAL DATA FOR THE SAMPLES TESTED ARE PRESENTED IN TABULAR AND GRAPHIC FORM. THE TECHNIQUES HAVE GOOD REPRODUCIBILITY, AND IT WAS POSSIBLE TO DISTINGUISH 38 OF 40 GLASS SAMPLES FROM EACH OTHER USING COMBINED TECHNIQUES. SAMPLE PREPARATION, ANALYSIS, AND CALCULATION OF TWO GLASS SAMPLES REQUIRES APPROXIMATELY 1 HOUR. TWO OR MORE ANALYSES PERFORMED ON EACH SAMPLE WILL INCREASE THIS TIME, BUT RESULTS IN GREATER PRECISION. EMISSION SPECTOGRAPHY SHOULD BE USED AS A LAST RESORT BECAUSE OF ITS LONGER ANALYSIS TIME AND BECAUSE DESTRUCTION OF THE SAMPLE IS NECESSARY. REFERENCES ARE INCLUDED. (JAP)