Abstract: The process of detecting the presence on a surface of at least one of bis(2-chloroethyl)sulfide and bis(2-chloroethyl)imine, including (a) providing a solution comprising at least one dyestuff selected from the group consisting of brilliant blue R, guinea green B, neutral red, and lissamine green B, which at least one dyestuff is capable of fluorescing and is capable, when applied as a solution, of forming an adduct with at least one of bis(2-chloroethyl)sulfide and bis(2-chloroethyl)imine when present on a surface, which at least one adduct, is capable of fluorescing in a spectral range which is different from that of the corresponding at least one dyestuff; (b) applying the solution to the surface; (c) irradiating the surface onto which the solution has been applied with light having a wavelength effective to excite the at least one dyestuff and, when present, the at least one adduct, and induce light emission by fluorescence therefrom; (d) measuring the wavelength of the light emitted from the surface; and

Abstract: For determining the charging of a charcoal filter with gases and vapors the acoustical and the electrical impedance of the charcoal layer are measured. The more the filter is charged the greater will be the density of the charcoal layer and therewith its acoustical conductivity. The charging of a charcoal layer with water vapor results in an increase of the acoustical as well as of the electrical conductivity. By comparing the acoustical impedance and the electrical impedance respectively of a partially charged charcoal layer with the impedance of a non-charged charcoal layer and by subsequent comparison of the impedance changes caused by such charging the influence of water vapor can be eliminated. A signal is generated corresponding to the charging of the charcoal filter with other vapors and gases which signal may be used for indicating the condition of the filter and for generating an alarm if the filter becomes exhausted.