Legal chemistry and scientific criminal investigation / by A. Lucas.

  • Lucas, A. (Alfred), 1867-1945.
Date:
1920
Catalogue details

Licence: In copyright

Credit: Legal chemistry and scientific criminal investigation / by A. Lucas. Source: Wellcome Collection.

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    of the laboratory work book in which the original facts and figures were entered at the time the article was examined. Articles are frequently very badly packed and very in- adequately marked. This is not the fault of the expert but, by drawing attention to it each time it occurs, improvements in this respect may be brought about. The commonest faults are the use of wet or dirty bottles, dirty corks, insuffi- cient protection of glass vessels during transit, the use of thin cardboard boxes which cannot be closed securely and which easily break or become forced out of shape, and so allow the contents to escape, the use of ordinary correspon- dence envelopes from which finely powdered materials always leak, the packing of several articles in one parcel in such a manner that contamination of one with another is almost inevitable, and the use of sealing wax on the corks of bottles containing alcoholic liquors or other liquids in which sealing wax is soluble. Many articles too are received without sufficient marks of identity or else bear such marks only on the outside wrapper which has to be removed. It does not seem to be sufficiently recognized that ordinary gummed labels do not adhere well to tins or to painted or glazed surfaces, with the result that such labels frequently come off and the articles are left without any means of identification. For small samples of dry material the round cardboard boxes, which are sold in nests of different sizes, will be found very useful. Oblong envelopes with the opening at the end are also very satisfactory, and such envelopes are made in all sizes specially for holding samples, and many have ingenious methods of fastening. As already mentioned, ordinary correspondence envelopes are most unsuitable and should on no account be used. 2. The Examination.—The first step in the examination of an article is to scrutinize it carefully and to write down in the laboratory note-book 1 a full description of its appear- ance. The outside of the package, the manner in which it is secured and particulars of the seals, if any, should first 1 The note-book should be of good quality, with ruled paper and a stiff back, which should not be of the glazed black material so often used, but of some substance on which it is possible to write. All entries in this book should be in ink.