skip navigation

PUBLICATIONS

Register for Latest Research

Stay Informed
Register with NCJRS to receive NCJRS's biweekly e-newsletter JUSTINFO and additional periodic emails from NCJRS and the NCJRS federal sponsors that highlight the latest research published or sponsored by the Office of Justice Programs.

NCJRS Abstract

The document referenced below is part of the NCJRS Virtual Library collection. To conduct further searches of the collection, visit the Virtual Library. See the Obtain Documents page for direction on how to access resources online, via mail, through interlibrary loans, or in a local library.

 

NCJ Number: 47269 Find in a Library
Title: DISCRIMINATION BETWEEN SAMPLES OF WINDOW GLASS BY COMBINING PHYSICAL AND CHEMICAL TECHNIQUES
Journal: JOURNAL OF FORENSIC SCIENCES  Volume:23  Issue:2  Dated:(APRIL 1978)  Pages:250-262
Author(s): J ANDRASCO; A C MAEHLY
Corporate Author: American Soc for Testing and Materials
Promotions Manager
United States of America
Date Published: 1978
Page Count: 13
Sponsoring Agency: American Soc for Testing and Materials
West Conhohocken, PA 19428-2959
Statens Kriminaltekniska Laboratorium
Linkoping, Sweden
Sale Source: Statens Kriminaltekniska Laboratorium
Fack, S-581 01
Linkoping,
Sweden
Type: Report (Study/Research)
Format: Article
Language: English
Country: United States of America
Annotation: TWO PHYSICAL TECHNIQUES, MEASUREMENT OF REFRACTIVE INDEX AND DENSITY, AND TWO CHEMICAL METHODS, ENERGY DISPERSIVE X-RAY ANALYSIS AND EMISSION SPECTOGRAPHY, ARE DESCRIBED AND APPLIED TO ANALYSIS OF 40 WINDOW GLASS SPECIMENS.
Abstract: 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)
Index Term(s): Evidence identification; Glass analysis; Research; Spectroscopy; Techniques; X-Ray Technology
To cite this abstract, use the following link:
http://www.ncjrs.gov/App/publications/abstract.aspx?ID=47269

*A link to the full-text document is provided whenever possible. For documents not available online, a link to the publisher's website is provided. Tell us how you use the NCJRS Library and Abstracts Database - send us your feedback.