Mass spectra obtained with the disjunctive d.c.-spark in vacuum show considerable improvement in accuracy and reproducibility over the conventional r.f.-spark of the DEMPSTER type. Higher ion currents increase the speed of analysis. A number of mass spectra were produced with a spectroscopic steel standard. The methods of visual and photometric spectrum evaluation are discussed in detail, using two quantities defined as “element sensitivity” and “normalized ionization sensitivity”. The former is a measure of how much more sensitive a given element can be photographically detected with the mass spectrograph than the main component of the sample (matrix element), while the latter indicates how much more sensitive multiply-charged ions of an element can be detected on the plate than singly-charged ions of the same element. Both element- and ionization sensitivities are reproducible to within approximately 20%. Furthermore, it is found, for most elements investigated, that the lines due to doubly-charged ions are more intense than those due to singly-charged ions and that the differences of element sensitivities of various elements decrease for ions of higher charge. The reproducibility of multiply-charged ions permits their use in the quantitative analysis of the sample.