It is a well known thing in spectrography, that if one is making quantitative determinations of some chemical element in one sort of material, and then turns to determine this element after the same method in another material, having a base substanse essentially different from the first, a trial of the validity of the calibration curve for the new material (the new base) is necessary, often with the result that a new calibration curve must be constructed. In the most favourable case the calibration curves constructed for different bases, are identical or nearly identical, but as a rule one must be prepared to find the curve displaced, because the intensities of the spectral lines applied, may be influenced by the physical conditions prevailing in the are, and by the manner in which the elements evaporate from different base substances, and these conditions may vary when the dominating su bstanse is e. g. lime, silicates, or metals.