Abstract
An intermittent arc source unit was constructed for the determination of small amounts of silicon and tin in iron and steel. The triggering spark current of the unit was wholly electronically controlled with thyratrons and it was possible to change continuously the frequency of interruption and the ratio of arc duration to the time the current is interrupted. This source unit, combined with either a large Littrow-type or a medium quartz spectrograph, proved to give satisfactory results in determining 0.008 to 0.163% Si and 0.010 to 0.145% Sn.
