The conventional method of quantitative spectrochemical analysis employing bright-line spectra and photographic recording is discussed with reference to the various steps involved. The steps which may be eliminated by the application of direct photoelectric recording are considered and a method based on this type of recording is discussed. A detailed comparison of the two methods is made which leads to the conclusion that only by designing an entirely new spectrum-dispersing instrument can “direct reading” be made sufficiently flexible for general adaptation. Such an instrument is considered in detail together with suitable analytical procedure for its use. The probable speed and accuracy attainable are illustrated by examples. Present limitations and future developments are considered. A proposed instrument is announced.
M. F. HASLER and H. W. DIETERT, "Direct Reading Instrument for Spectrochemical Analysis," J. Opt. Soc. Am. 34, 751-756 (1944)