Poisons : their isolation and identification / by Frank Bamford.

  • Frank Bamford
Date:
1940
Catalogue details

Licence: In copyright

Credit: Poisons : their isolation and identification / by Frank Bamford. Source: Wellcome Collection.

    17/376 page 5
    SPECIFICITY OF TESTS the better, but they must be fully trained and experienced as analysts. Many of the tests to be described later may appear simple enough to be left to a laboratory assistant ; nevertheless, there may be pitfalls. It is not sufficient to know how to carry out an analytical process ; one must be acutely conscious of the possible fallacies, and this implies knowledge and experience extending far beyond the immediate question of applying tests for a substance whose presence is suspected. There are few chemical tests which are absolutely and beyond question specific for the substances they are supposed to identify. It follows, therefore, that if a positive result can be obtained in one test only, the report must be very carefully expressed. Indeed, it may be the duty of the chemist, should he fail to confirm one result by a test of different character, to report that the result is negative. This point will be dealt with more fully in the chapter on alkaloidal poisons, but it may be laid down as a universal rule that no positive statement must be made as to the presence of poison on the evidence of a single test. Further, when the test depends on changes of colour a chemist should doubt the evidence of his own eyes 5 he should consult a colleague whenever possible. In poisoning cases of which the complete history is known, i.e., in which the symptoms have been recorded by an experi- enced medical practitioner and in which observations at the autopsy have given indications of a poison of a definite kind, complete chemical analysis will seldom be required. The chemist, unless he is himself a medical man, may expect to leceive guidance from his medical colleague 5 and when such effective co-operation exists the analyst’s work may be restricted to the search for poisons of a particular group. The ideal conditions are attained when the medical officer’s repoit at the autopsy confirms the opinion of the physician (if any) who has attended the patient and is itself confirmed by the findings of the analytical chemist. It is usually recommended that not more than one-third of the available material should be used for the first analysis, the remaining two-thirds being reserved for repetition and for control by another analyst. This course is certainly advisable, and should be followed whenever possible. However, in the examination of viscera for alkaloids or similar drugs the
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