SEPARATION OF BLOOD STAINS AND OTHER SOLUBLE MATERIALS BY CAPILLARY ACTION.

This article discusses the separation of blood stains and other soluble materials by capillary action. Blood stains particularly and some other soluble materials as well, are located in evidence in such a form as to make their removal and testing by conventional methods exceptionally difficult. For example, blood may be mixed with soil, dry leaves, wood fragments and miscellaneous debris in such a way that ordinary methods of testing are ineffective. Furthermore, blood may be distributed over irregular objects and in very small quantities, and it may have been spread and diffused by washing and other procedures to such an extent that its recovery is very difficult. A technique has been developed which eliminates many of these difficulties and allows very precise and sensitive testing for blood in numerous conditions which otherwise could not be carried out readily or perhaps at all. The essential technique involved regardless of the type of material from which blood is removed, is the application of a filter paper strip which is kept wet with the water used to transfer the blood and which allows it to creep up by capillary action and evaporate from paper at a point above the location of the blood-containing material. The soluble materials are carried to the highest point reached by the water and concentrate there in a narrow band.