A controlled study was carried out on 600 samples of various types of white and colored paper obtained from 10 different paper manufacturers with known production histories and dates. Neutron activation analysis was employed to measure the characterizing trace elemental compositions. Results indicated that (1) the papers examined were uniform with respect to their trace elemental compositions, (2) papers produced by different manufacturers are readily distinguishable qualitatively and/or quantitatively, (3) different batches of paper produced by the same manufacturer are generally qualitatively similar if produced within a short span of time (however, these specimens can be distinguished by quantitative analysis of the trace elements), and (4) different batches of paper produced by the same manufacturer at least 1 year apart are readily distinguishable qualitatively and/or quantitatively.

A technique is described for the analysis of the plastic explosive, C-4. The method involves a chloroform extraction of the sample and an infrared examination of the extract. Problems that may be encountered in attempting to identify C-4 are discussed and solutions to these problems are proposed.

A study of colored paints was made to determine to what extent individual paint samples can be characterized by neutron activation analysis. Approximately 300 samples of red, white, blue, and green paints from the major manufacturers in the United States were examined. It was found that paints of the same color produced by different manufacturers could be distinguished by this technique. Batch-to-batch variations between paints from the same manufacturer were observed, and it was found that in a small number of cases no differences were detected.

A technique providing both analytical and toolmark results for lead fragments from bullets is discussed. It permits the nondestructive recovery of bullet fragments from soft cadaver tissue and was used with a plasma asher in an actual homicide case. The lead fragments are examined by neutron activation analysis (but other analytical techniques can be used) for their antimony and arsenic content and by microscopy for matching toolmarks.

The special considerations which must be given to the collection and handling of physical evidence from the scene of a crime for a forensic laboratory are presented. Specifically covered are the handling of physical evidence from criminal acts which violate those jurisdictions comprising an important segment of the responsibilities of the Bureau of Alcohol, Tobacco and Firearms in the U.S. Treasury Department. Many of the unique characteristics of this unusual type of sampling are discussed, particularly those aspects differing markedly from the more routine types of chemical sampling. Topics covered in detail include the following: the selection of materials of possible evidential value; the process of collecting and gathering such items of interest; the importance of marking and labeling properly; the packaging of these materials; their preservation; the proper transmission to the forensic laboratory; and the associated legal requirements which must be adhered to throughout this procedure.