GB473043A - - Google Patents

Abstract

Abstract 473,043. Detecting finger-prints &c. ELECTRICAL RESEARCH PRODUCTS, Inc. Dec. 23, 1936, No. 35220. Convention date, Jan. 11. [Classes 97 (i) and 98 (i)] In order to detect finger-prints, or other marks containing a fatty substance, which are normally invisible or visible only with difficulty, the marks are first treated to fix the fatty substance, then treated with a liquid which fluoresces in ultra-violet light, and then viewed by ultra-violet light. The fixing operation is preferably effected by using Fleming's reagent, consisting of a mixture of osmic acid, chromic acid. and glacial acetic acid. The treating material for producing florescence preferably consists of a coal tar dye such as diazine fast yellow. The Figure shows the viewing-apparatus comprising a housing 3 for a source of light rich in ultra-violet rays, the light passing through a filter 6 transparent to ultra-violet into a chamber 9 having at one end a door 10 on which the object to be viewed may be mounted or through which it may be placed in the chamber. The object is observed by an eyepiece 12, the observer being protected from direct light by a shield 17. Instead of making visual observation, photographs of the object may be taken by using appropriate lenses at 12.

Inventors

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Bibliographic Details