The relative atomic weights of nitrogen and sulphur

Abstract

In 1905, nitrogen sulphide was being prepared and used in large quantities at University College, Bristol, and it was due to a suggestion of Prof. Francis that it might prove a suitable substance for determining the relative atomic weights of its constituent elements, that the present research was under­taken. Ho direct measurement of the ratio N : S has previously been made, and since the atomic weight of sulphur is still uncertain, a useful step is gained in acquiring an accurate knowledge of that ratio. The compound N 4 S 4 has the advantage of containing no other element. Preparation and Purification of Nitrogen Sulphide. All the nitrogen sulphide employed in this research was made in Bristol by Prof. Francis and Mr. O. C. M. Davis, by passing dry ammonia into a benzene solution of sulphur chloride. The main products of the reaction are nitrogen sulphide, nitrogen, and hydrogen chloride. The sulphide which was deposited on concentrating the benzene solution contained traces of sulphur. We used as our raw material some sulphide which had stood for many months in the air, and which contained a large proportion of free sulphur as well as ammonium salts. The mixture was extracted with pure dry benzene in a Soxhlet apparatus, and the resulting solution contained all the nitrogen sulphide and relatively little sulphur; on cooling, large needles of nitrogen sulphide were deposited, together with a little finely divided sulphur. The crystals, after being twice washed with cold carbon disulphide, and then with benzene, were powdered on a porous tile and placed in a desiccator containing calcium chloride and cocoanut charcoal.