J. V. Eyre, E. S. Salmon and L. K. AVormald 287 



amount of sulphide sulphur present in the solution was found to be 

 6-24%. 



Yellow ammonium sulphides. Eleven different solutions containing' 

 ammonium polysulphide were used during the course of this work. 

 The analyses of these solutions are given on p. 306. Briefly described 

 their mode of preparation was as follows^. 



Solution I. This solution was made by saturating 200 c.c. of a 

 10 % solution of ammonia in water at 17° C. with sulphuretted hydrogen 

 gas and then adding 400 c.c. of 10 % ammonia solution and 1000 c.c. 

 of water. To this mixture 24 grms. of flowers-of-sulphur were added 

 and when this was completely dissolved the clear solution formed the 

 Stock Solutioji No. I. The specific gravity of this stock solution was 

 1-001 at 15° C. 



Solution II. This was prepared by saturating 1-5 litres of 30 % 

 aqueous ammonia with hydrogen sulphide gas until the specific gravity 

 of the liquid rose to 0-955. To this solution 3 litres of 30 % ammonia 

 were added and 567 grms. of flowers-of-sulphur. Tliis gave a dark 

 brown fluid which had sp. gr. 0-950 and showed a tendency to deposit 

 sulphur when largely diluted with water. 



Solution III. This was prepared from Solution II by passing more 

 sulphuretted hydrogen gas through the liquid until the specific gravity 

 reached 1-05. This Stock Solution III was more stable when diluted with 

 water than Solution No. II from which it was prepared. 



Solution IV. To 500 c.c. of Stock Solution No. II, 55 grms. of flowers- 

 of-sulphur were added and a current of sulphuretted hydrogen gas 

 passed through the liquid until all the sulphur was dissolved. The 

 resulting liquid had a sp. gr. 1-036 and was very dark in colour. When 

 diluted largely with water a considerable deposition of sulphur occurred 

 after about ten hours. 



Solution IV A. This solution was prepared from Solution IV by 

 allowing a current of sulphuretted hydrogen gas to pass through the 

 solution until its specific gravity became 1 -087. Solution No. IV A proved 

 to be less liable to deposit sulphur when diluted with water and allowed 

 to stand. 



Solution V. A solution of ammonia in water (sp. gr. 0-987 at 15° C.) 

 was saturated with sulphuretted hydrogen gas and an aqueous solu- 

 tion of ammonia was added until on testing with copper sulphate 



1 Several of the solutions used were made according to the details given by Bloxani. 

 Vide "The Sulphides and Polysulphides of Ammonium," Trans. Clietn. Soc, 67, 1895, 

 pp. 277-309. 



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