California Association of Criminalists
Since 1954
CHRISTIANSEN EFFECT IN REFRACTIVE INDEX MEASUREMENTS
John E. Davis, Oakland Police Laboratory, Oakland, Ca.
A report of studies involving the Christiansen effect in the determination of refractive index of glass was given. Bromobenzene or nitrobenzene and xylene mixtures were used with a 48 mm microscope lens, with a constant temperature microscope stage to produce refractive index measurements with a precision of .002 (white light) and .001 with sodium light, using Becke line technique. It was concluded that this method is worthy of trial by anyone interested in expediting refractive index determinations.
ACID PHOSPHATASE REACTION IN SEMINAL STAIN TESTS
William Penprase, Los Angeles Police Department Criminalistics Laboratory
A critical evaluation of the Hazen method (Proceedings of American Academy of Forensic Sciences, 1955) was given, and procedures involving quantitative colorimetric end points was discussed. Vagaries of molybdenum blue color development and its failure to follow Beers law were pointed out. It was concluded from the extent of the present experimental work that the Hazen method in connection with stains encountered in criminalistics work is subject to so many interferences that it cannot be considered a reliable or specific test for seminal material.
RESTORATION OF DECOMPOSED FINGERS FOR FINGERPRINTS
Hilliard Reeves, C.A.C., Criminologist, Richmond Police Department
A report of technique was given in which dehydrated finger tissue is soaked in water or saline solution, never formaldehyde, then followed by immersion in hot neetsfoot oil, to restore pliability. The oil is then removed with chloroform and, after being inked, the tissue is rolled to produce good quality prints.
MANUFACTURING PROCESSES OF SMITH & WESSON REVOLVER
Sgt. E.L. Uhde, Los Angeles Police Department Criminalistics Laboratory
Moving pictures were presented, with commentary, based on personal observations at the Smith & Wesson factory. This interesting presentation gave an excellent orientation and insight into the process of gun-making and the basis for marks which are involved in firearms identification procedures. It was stated that spectrographic analyses of bullet compositions are always inconclusive as to identity problems. Emphasis was placed on the conclusiveness of matching toolmarks in the identity problem.
QUESTIONED DOCUMENT PROBLEMS
John Harris, Los Angeles County Sheriff's Office
Mr. Harris discussed general principles of approach to the questioned document examination problem, going into broader aspects of identification problems and evaluations, which was very well received.
BULLET COMPARISON PROBLEMS OF IDENTITY
Paul L. Kirk, Professor of Biochemistry & Criminology, University of California, Berkeley
A study of bullet comparisons in connection with a thesis leading to a degree of Master of Science by Alfred Biasotti was given and summarized. Consideration was given to the interpretation of matching and non-matching lines involved in juxtaposition microscopic comparisons. Important conclusions were that more than three matching lines without intervening non-matching lines on lead bullet comparisons which occur more than once around the periphery of the phased bullets is conclusive of identity of gun barrel. In connection with jacketed bullets, more than four matching lines under the same circumstances are conclusive. Single line coincidences were determined to be inconclusive. This study appears to be the most comprehensive yet made in connection with this subject.
IDENTIFICATION OF BENZEDRINE & HOMOLOGUES BY PAPER CHROMATOGRAPHY
J.W. Brackett, Jr., Assistant Criminalist, Laboratory of Criminalistics, Santa Clara County, San Jose
A discussion was given, with a method for the individualization of benzedrine and 12 homologues and similar compounds. The field application of this method is the appearance on the market of benzedrine-like inhalers to which the Dangerous Drug Act consists of making paper chromatograms of the sample material, using known materials for comparison. The conditions involve Whatman No. 1 paper, prebuffered with 5% sodium dihydrogen sulfate and dried in an oven; 50% normal butanol saturated with water, containing 2% picric acid; three hours development using ascending technique followed by potassium iodoplatinate developer on the dried chromatogram. All of the studied compounds were differentiated by comparative Rf values, or color developed, excepting optical isomers.
TOOL MARK CASTING & COMPARISONS
Don Harding, C.A.C., Pasadena
A discussion of the various commercially available plastics and the fidelity of casting reproducibility were discussed. A particularly interesting casting material was named as Duraflex, available from the Reliance Dental Manufacturing Company, Chicago. Reference was also made to a study since published by Mr. Biasotti in the Journal of Criminal Law, Criminology, and Police Science, Vol. 47, No. 1, 1956.
ELECTROPHORESIS OF INKS
Clifford Cromp, Los Angeles Sheriff's Office Laboratory
Results of experimental work were presented using a simplified electrophoresis technique. It was concluded from a study of ink aging that no significant changes can be detected in connection with the age of ink by this method.
STANDARDS OF ETHICAL CONDUCT IN DEFENSE AND CIVIL CONSULTING
Lowell W. Bradford, Director, Laboratory of Criminalistics, Santa Clara County, San Jose
A discussion on the problems encountered in experience was given, and points were taken up which should be agreed upon and settled before undertaking a defense case. The various mechanisms of procedure were discussed.
