1. The systems used are not volume-dependent. for the identification and test of purity by means of test liquids, where, e. g., glycerol is used for aldehydes and ketones, glycol for ethereal oils, ethylene cyanide for benzene and its homologues and halogen derivatives. for quantitative determination of binary mixtures, when still other test liquids are employed: paraffine oil, butanol, acetophenone.