I. Researches in spectrum photography in relation to new methods of quantitative chemical analysis. Part II

Abstract

This paper includes an introduction recording the methods which have been proposed by different authors for the quantitative estimation of various metallic elements. A n account is then given of the length and strength of metallic lines in solutions of definite strength. Under given conditions each solution emits a characteristic spectrum. In the case of magnesium, a minute description is given of the spectra presented by various solutions containing from 1 per cent. to 0·00000001 per cent. of the metal, but in the case of other elements tabular descriptions of the spectra of solutions containing 1, 0·1, and 0·01, in some instances 0·001, of metal are given together with carefully drawn maps. The substances thus treated of are magnesium, zinc, cadmium, aluminium, indium, thallium, copper, silver, mercury, tin, lead, tellurium, arsenic, antimony, and bismuth. The sensitiveness of the spectrum reaction is practically unlimited when applied to magnesium compounds dissolved in water, since it was shown that with a given length of spark, 1/10000000 of a milligram could easily be detected; when, however, the strength of spark was greatly increased, but the striking distance between the electrodes left unaltered, the sensitiveness was increased ten thousand-fold. In point of fact, one part of magnesium was detected in 10,000,000,000 parts of water, the lines seen under these circumstances being those with wave-lengths 2801·6 and 2794·1. The spectrum reaction of arsenic is the weakest, those of antimony and tellurium are also weak, while that of bismuth is not strong. In fact it is noticeable that the more strongly basic elements are those with the most persistent lines.