Spectrographic determination of minor elements in portland cement

A rapid spectrographic procedure for the determination of t he minor metallic elements in portland cement is described.The method shows promise of casy extension to cement raw materiaLs and many ceramic materials, provided reli able standard samples of t hese materials a re available.In the application of the method to port land cemc nt, se ven minor elements were dete rmined.The p recision in terms of probable e rror of a ingle determinat ion is within 3 percent of t he oxide concentration for a luminum , iron, magnesium , manganese, and t itanium ; 5 percent of thc N a 20 COllcen tration ; and 8 percent of t he 1(20 concentration .Other m inor elements, s uch as lithium, stro ntiu m , chromi um , zircon ium, and vanad ium , may r eadily be included.The spectrograph ic analyses of 21 portland cements are compared with chemical results for a n estimate of t he accuracy.Salient features of t he pr ocedure a r e (1) employing pellets consisting of t he ceme nt powder, w ith graphite as a bindel', cobalt oxide a s an i nternal standard, an d potassium nitrate as a buf-Ier , (2) applying t he pellet as an electrode for excitation by an ove rdamped condenser discharge, and (3) photographing the spectrum with a step sector and a d iffu sing screen for obtain in g un iform ity of illumination.