Treasure of the Past: II. The Atomic Weight of Bromine
A considerable amount of work has been done in order to determine the atomic weight of bromine and the oft-repeated comparison of the atomic weights of silver and bromine makes it seem that this ratio is known with considerable accuracy. The value accepted for bromine, however, rests almost entirely upon that of silver, and it is of interest and importance to obtain a ratio between it and some other element. For chlorine a number of determinations of the ratio of hydrogen to chlorine in hydro-choleric acid have been made, both by purely physical and by chemical methods. For bromine similar comparisons have not been made. Since the determination of the ratio chlorine: hydrogen was carried out with reasonable ease, it seemed probable that the method might be advantageously applied for the purpose of determining the ratio between hydrogen and bromine. The method, which was employed by Noyes and Weber, was found to give good results in this case. The initial difficulties to be overcome were somewhat greater, which was rather unexpected. They were largely due to the physical properties of hydrobromic acid gas and were eliminated after the method had been studied for some time and slight alterations in the method of manipulation had been introduced. It is not necessary to go into a discussion of previous work on bromine here. The entire subject matter is to be found either in Clarke's A Recalculation of the Atomic Weights or in Abegg's Handbuch, in the chapter on Fundamental atomic weights.