Mr. Redlich. As I understand it, Mr. Gallagher, one of the reasons why this test is considered unreliable for purposes of determining whether or not someone has fired a weapon is the fact that the elements which react with the reagents in the paraffin test are found in a variety of common substances. Is that correct?
Mr. Gallagher. The diphenylamine or the diphenylbenzidine tests are not specific. They react with many ingredients and for this reason the results obtained from such tests are difficult to interpret.
Mr. Redlich. And when I asked you to evaluate the results of the neutron activation test performed on the hand casts in the light of the contents of Gallagher Exhibit No. 1, do I understand your answer to be that in the case of the neutron activation analysis it is possible to make a valid determination as to the presence of the elements barium and antimony, notwithstanding the fact that the elements barium and antimony are found in common substances and not merely found in primer residues.
Mr. Gallagher. The determination of barium and antimony by neutron activation analysis is specific. Although there are commercial products which contain the elements barium and antimony, these components in many of these commercial products are not as available for contaminating purposes as are nitrates and oxidizing agents detected by the diphenylamine or diphenylbenzidine tests.
Mr. Redlich. So that the differences between the neutron activation analysis and the paraffin test for nitrate residues relate both to the question of the availability of the nitrates and oxidizing agents in the paraffin test as compared to the barium and antimony in the neutron activation analysis, and also to the fact that in the paraffin test for nitrate residues, the result is not necessarily specific as to nitrate residues, whereas in the neutron activation analysis for the presence of the elements barium and antimony, the results are specific to the elements barium and antimony. Is that a correct statement?
Mr. Gallagher. Yes. And furthermore, in Gallagher Exhibit No. 1, it says that paint, for example, contains both barium and antimony—this does not mean that every sample of paint contains barium and antimony. And so it is with the other items mentioned in Gallagher Exhibit No. 1.
Mr. Redlich. All right. Now let us turn to the cheek casts, Mr. Gallagher. Could you tell us the results of your examination of the cheek casts with reference to the presence of the elements barium and antimony?
Mr. Gallagher. Barium and antimony were found on the cheek casts. However, when the cheek cast was analyzed, both surfaces of the cheek cast were studied. That is, the surface adjacent to the skin of the subject and the surface away from the skin of the subject, or the outside surface of the cast.
Mr. Redlich. For our record, let us call the surface adjacent to the skin the inside surface, and the other surface the outside surface.
Mr. Gallagher. The outside surface of this cast was found to contain barium and antimony—actually more barium was found on the outside surface of the cast than on the inside surface.