It has been known for some time that in spectrographic analysis each element present has some effect upon the other elements present. Our investigation of the effect of the alkali metals on calcium showed that, in general, the intensity of the spectral lines of calcium increased with an increase in the percentage of the alkali metal present. However, there is a decrease in the intensifying effect at the higher concentrations. The chlorides of the alkali metals used were in concentrations varying from 1.0 per cent to 0.031 per cent, and the concentrations of the calcium solutions used varied approximately over the same range. Slides were used to show the apparatus used (including the wedge sector), typical spectrograms, and also to show some of the data obtained in graphical form
