Instruments. orobablv more than anv other sinele factor. represent the s$histication of the course to students. ~ h e i may not fully understand the operation of all instruments listed below, but they learn to use them, when to use them, and the limitations on the data produced by them. balance and scale Spectronic 20 (UV-Vis) liquid refractometer infrared speetrophotometer (spectra only) polarizing microscope melting point apparatus thin layer chromatography set-up
micrometer spectroscope gas chromatograph stereahinocularmicroscope compound microscope comparison microscope pH meter
Two textbooks are used for the course, one with most common material for a class of this tvue'. and the other of illustrations and case s t u d i e ~ T . ~h e k t e r is intended for practitioners in the field, but I have found it ideal to supplement my own laboratory exercises because the subject matter comes from actual cases and the photoaraphic reproduc. . tions are excellent. Evidence, Scenarlos, and Examples
Finallv. I illustrate the course with real cases such as the following; in which a chemist, testifying as an expert witness for the urosectution, concluded that heroin was present in a particular sample on the basis of several tests. Students in the class will already have become familiar with the rather uniquechemical tests reponed and will know the limitarions on earh test by the time we present this illustration. 1) Obserootion: Marquis Reagent turned blue-violet. This color
test givesa blue-violetcolorwithnearlyallopiates. His conclusion: an opiate is present; my conclusion: an opiate is present. 2) Obseruotlon: Zwikker's Reagent (cone. nitric acid) turned blue. Although this color test may be used to test for the presence of heroin, there is a strong indication that the colorformingreaction is with a degradation product of heroin rather than with heroin itself. The literature says that a positive test is an "emerald green" color. His conclusion: indicates heroin is present; my conclusion: there is substantial doubt that heroin is present, although it may have been there at some time in the past. 3) Obseruatian: Marme Reagent (potassium tetraiodocadmate) produced cubic crystals. This is a microcrystal test in which one examines the morphology of crystals that are formed. Usual practice is tocompare the shapeof the crystal with those formed between the reagent and a known exemplar sample. This analyst did not use an exemplar. His conclusion:confirms the presence of heroin; my conclusion: inconclusive test because an exemplar was not used, nor did his description of crystalline shape match the reported shape published in the literature. 4) Obseruotion: When the sample was treated with acidified ethanol, the odor of ethyl acetate was detected. His conclusion: proves the presence of heroin, which contains the acetyl functional group; my conclusion: confirms the presence of anacetyl group. Many compounds beside heroin contain aeetyl groups; if heroin were present in the sample, it would have reacted this way, but this test does not prove that the sample was heroin. 5) Obseruatian: When the samole was treated with aoueous silver nilra1e.n whitr precipitat~furmrd. H i b runrlusion: rnmplr was heroin hydrorhloridr: my ronclurion: somr autmtancc aau prrsent as a chloride soh or mixrd u i i h an inurpnnicchloride, the test says nothing about the sample being heroin T h e purpose of this example is not to show that the chemist made a mistake, although that is a logical conclusion one
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Saferstein, Richard. "Criminalistics: An Introduction to Forensic Science," 2nd ed., Prentice-Hall. Inc., Englewood Cliffs,NJ, 1981. Osterburg. J. W., "The Crime Laboratory." 2nd ed., Clark Boardman Co., New York, 1982.
might draw. Rather, the purpose is to enable students t o understand the limitations of the particular tests chosen in this common kind of case. They should have learned during this exercise that one cannot draw conclusions and testify t o results when exoerimental observations do not suooort . . the conclusion. hey should ha\.e learned that one needs to be careful in iatervretine what is written in a reoort. Illuiitrated problems such-as this, and those in the case studies hook, provide students with a good understanding of bow scientific information is obtained and used. In summary, this course combines a subiect matter of interest r u the students with a substantial scientific content ana is an effecti\.e way to communirate the principles and processes of the science to nonscience students. After 10 years of teaching Forensic Science, I a m convinced that courses of this tvoe serve as a useful mechanism bv which science can be co&nunicated. Students will accept the work and the disciuline when thev see how it fits in with their own interests.
Forensic Science: A Way to Introduce Scientific Techniques to Nonsicence Majors W. Glenn Essllnger West Georgia ~ o l l & e Carrolltan. GA 301 18
The idea of science as a method rather than a body of knowledae is not widelv. auureciated outside of science. And .. it will not be unless we, as scientists, have the opportunity to teach more nonscience students. All too often, our ideas, objectives, and methods are conveyed only to a few captive, select students. We must accept part of the blame for this. Too often we allow nonscience major courses to be taught by less than the best instructors, ao alona with an image of science and scientists as stuffy and arcane, and presentmaterials a t a level that only discourages the average student. Is it anv wonder then that we have onlv a few cantive students tb teach? T o turn this trend arounh, to again :ommunicate scientific methods to larger groups of students, I believe that we must make more of an effort to show them the importance of science in their evervdav . . lives. Alone the way, we must change the image of both ourselves an; our subject. 6 n c method of introducing both the role oisrienceand the scientific mrrhud to students is through a course in forensic science. Because the crime rate has ieached astronomical numbers and is climbing, students recognize the need for criminologists. They want to understand, up to a point, what must be done in order to solve a crime. However, they do not want to hear us.. sav. . . talk about details of neutron activation. atomic absorption, chromatography, etc., because thev do nor understand the nrinrioles hehind these kinds of instrumentation. Instead, they d a n t to he able tounderstand what it means to say that through instrumentation the suspect was placed a t the crime scene, his blood type matched that found a t the scene, etc. In other words, we must walk before we run with our students. In 1977, our department introduced a course in forensic science. Recognizing that students will not participate in science courses as electives, we also obtained approval to include this course in the prescribed "core" curriculum. We felt that such acourse would have inherent appeal because of people's interest in solving sensational crimes. Our first class in 1977, consisting mostly of police officers, was introduced to techniques of securing a crime scene and of collecting physical evidence and included in-depth discus~
Volume 62
Number 9
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September 1985
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