The speaker emphasizes guidelines for evidence handling such as placing a letter on the outside of a package and putting flammable liquids such as gasoline or turpentine into tightly sealed, clean containers. The use of a gas chromatograph in laboratory work is shown by a series of charts illustrating the ability of the chromatograph to break down a complex compound or mixture into constituent parts. In addition, the speaker discusses flashpoint, the effectiveness of sniffers, factors affecting evidence collection, problems in distinguishing between different brands of gasoline, and the importance of speedy investigation.