Now let's see what standard texts say about the paraffin issue: (posted by Tony Simon) From: _Gunshot Wounds: Practical Aspects of Firearms, Ballistics, and Forensic Techniques_ by Vincent J. M. Di Maio, Elsevier Science Publishing Co., Inc., 52 Vanderbilt Avenue, New York, New York, p. 267, (1985). ------ The ability to determine whether an individual has fired a firearm is of great significance in the investigation of both homicides and suicides. Thus, over the years a number of tests have been developed in an attempt to fill this need. The first such test was the "paraffin test" also known as the "Dermal Nitrate" or "diphenylamine test." (1) It was introduced in the United States in 1933 by Teodoro Gonzalez of the criminal identification laboratory, Mexico City police headquarters. In this test, the hands were coated with a layer of paraffin. After cooling, the casts were removed and treated with an acid solution of diphenylamine, a reagent used to detect nitrates and nitrites that originate from gunpowder and may be deposited on the skin after firing a weapon. A positive test was indicated by the presence of blue flecks in the paraffin. Although this ~~~~~~~~~~~~~ test often but not invariably gave positive results on the hands of ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ individuals who fired weapons, it also gave positive results on the hands ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ of individuals who had not fired weapons because of the widespread distribution of nitrates and nitrites in our environment. The paraffin test is in fact nonspecific and is of no use scientifically. ------ (1) Cowan, M. E., Purdon, P. L. A study of the "paraffin test." J. Forensic Sci. 12(1): 19-35, 1967. And posted by McAdams: The following is from Charles O'Hara and Gregory L. O'Hara, FUNDAMENTALS OF CRIMINAL INVESTIGATION, pp. 820-821. The dermal nitrate test (paraffin gauntlet test) is a procedure designed to determine whether a suspect has recently discharged a firearm. Melted paraffin is brushed over the "shooting" hand of a suspect until a thin coat is obtained. The glove can be built up in layers by using thin sheets of fabric until it is about 1/8 inch thick. The diphenylamine reagent is prepared by adding 10 cubic centimeters of concentrated sulfuric acid to 2 milliliters of distilled water. To this is added 0.05 grams of diphenylamine. The reagent is dropped on the paraffin mold with a pipette. Dark blue specks appearing on the inner surface of the cast indicate a positive reaction. . . . Theoretically, the diphenylamine reagent is used to test for the presence of nitrates, which are contained in the residue of gunpowder blown back on the hand in discharging the firearm. . . . Objections: There are several scientific objections to the test as described above in its simplest form. The role of the nitrate on the hand is that of an oxidizing agent. Other strong oxidizing agents can produce the same effect. Hence, launderers, chemists, pharmacists, and other persons handling bleaches or other oxidizing compounds may have materials on their hands which would yield a positive reaction. Thus the test does not necessarily indicate the presence of nitrates, but establishes merely that an oxidizing substance is present on the hand. In brief, the test is non-specific. Another objection is concerned with the fact that there are many non-incriminating sources of nitrates such as fertilizers, explosives, tobacco, urine, and cosmetics. Certain foods also contain nitrates. Finally, some experimenters have found that it is possible to obtain a negative reaction from the ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ hand of a person who has recently fired many rounds of ammunition. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ There is plenty of evidence that paraffin tests give false negatives. -- Felix Chen felixc@engin.umich.edu ------------------------------------------------- After the above was posted on the Usenet, Lisa Pease replied saying that of course the forensics books say that the paraffin test can give false negatives, since the conspiracy has made sure that they said that. The following message was from a poster who found a passage dating well *before* the assassination. ----------------------------------------------- From: jhartman@crl.com (John L. Hartman) Newsgroups: alt.conspiracy.jfk Subject: Re: The Conspiracy Rewrote the Forensics Texts! Date: 27 Nov 1995 00:02:58 -0800 Lines: 47 Message-ID: <49brbi$481@crl2.crl.com> NNTP-Posting-Host: crl2.crl.com X-Newsreader: TIN [version 1.2 PL2] This is supposed to be a followup to John Mcadams posting. It is also my first message with the TIN newsreader. I happened to have "Firearms Investigation, Identification, and Evidence" by Hatcher, Jury, and Weller (The Stackpole Co., Harrisburg Pennsylvania copyright 1957) available. They discuss the Paraffin Test For Nitrates on pages 435 through 438. Some excerpts relating to false negative results: Describing FBI and other control tests of the method -- "They have found the most alarming inconsistencies. For instance, a woman who could not remember ever having had a firearm in her hand in her life gave positive tests for both hands. Further, men who fired guns all day were sometimes able to remove most of the evidence of this firing by an ordinary washing of their hands with the usual soap provided in rest rooms." The authors then reprinted an article from the FBI Law Enforcement Bulletin for October 1935 (Note the date) with the comment that the article is "still completely authoritative on this subject." In the article after a discussion of false positive results -- "On the other hand, it is well to know the limitations of the diphenylamine test which are due to the fact that in a great many instances one may fire a revolver or pistol without leaving any trace of gunpowder on the hand which may be detected by the test." (page 437)