Suppression of Certain Parts in Spark Spectra by Electronic Time Switching

An electronic device is described which renders a phototube sensitive only at prescribed but arbitrary intervals of a spark cycle. Such undesirable light, as air lines and continuous background, can then be suppressed. There is evidence that for spectrochemical analysis purposes the spectrum thus recorded photoelectrically combines the stability and reproducibility of the condensed spark with the sensitivity of the dc arc.