SEMI-ANNUAL SEMINAR (Spring 1956)
CALIFORNIA ASSOCIATION OF CRIMINALISTS
May 25-26, 1956
LOS ANGELES, CALIFORNIA
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.