An a. c. operated mass spectrograph of the Mattauch type.
A mass spectrograph for chemical analysis of solid samples has been developed. The Mattauch arrangement of a 31° 50′ electric deflection followed by a 90° deflection in a magnetic field was used in order to obtain a large mass range in focus on one plate. The accelerating and deflecting voltages, and the current for the electromagnet were obtained from stabilized rectifier circuits connected to the 60‐cycle a.c. supply. The electromagnet with 100 milliamperes gave a field of 18,800 gauss across a ⅛″ gap. During the introduction of the plate or insertion of new electrodes a gate valve was closed to isolate the spectrograph from the pumping system. In this way different samples could be examined rapidly. The ion source was energized by a compact Tesla transformer wound on Lucite cylinders. One exposure covered a mass range from any mass M to a mass 10M.
Modern Mass Spectroscopy
Publisher Summary This chapter describes the general theory, apparatus, and uses of the modern mass spectroscopy. Mass spectrographs and mass spectrometers are electronic instruments, which analyze substances according to the mass of the constituent elements and molecules present. The mass spectrograph is employed for determining what masses are present or to determine mass defects, while the mass spectrometer is used to measure the relative abundances of the different components in the mass spectrum. A number of physical arrangements have been used by the different workers in the field of mass spectroscopy to solve different problems. Direction focusing magnetic analyzers are the simplest mass analyzers used in modern mass spectroscopy. It is the ion detector which determines whether any particular analyzer is a mass spectrometer or a mass spectrograph. The first problem to which the mass spectrograph was applied was that of identifying the isotopic composition of the elements. The second major application of the mass spectroscope was the problem of determining the isotopic composition of the elements. The third important task to which the mass spectrograph was put was that of determining the exact masses of the isotopes.
Brownian Movements in Gases at Low Pressures
The essential improvements which the "oil drop method" introduced 
into the study of Brownian movements consisted in 
1. Enabling the observer to hold a given particle under observation as 
long as desired, even in a rarified gas, by counteracting the downward 
pull of gravity by the upward pull of an electrical field. 
2. Eliminating completely all uncertainty as to the resistance offered 
by the medium to the motion of the drop through it.