248 [Dr. E. W. Davy on a very singular 



assumed an orange tint, that almost immediately more or less 

 of a solid matter invariably separated from the liquid, appear- 

 ing at first of a bright orange or light red colour, from its being 

 suspended in the orange or red liquid, but that, after it was 

 separated from it by filtration and washing, it was found to 

 possess a light brown appearance. Whilst the changes just de- 

 scribed were taking place, it was also noticed that the mixture 

 became sensibly warm to the hand, and that the odour of the 

 sulphide disappeared, whilst that of ammonia and of chloroform 

 was easily detected. 



It was further ascertained that when the dark reddish-brown 

 liquid obtained in the way just stated was acidified with an acid, 

 it yielded a copious brown precipitate, which, though somewhat 

 darker in its colour than that which separates from the liquid 

 before the addition of the acid, appears to be essentially the 

 same compound, the difference of shade being probably due, at 

 least in some measure, to different amounts of free sulphur 

 present in each. 



As the principal feature of interest connected with the reac- 

 tion referred to, I considered, was attached to the formation 

 of the brown solid compound just noticed, a quantity of it 

 was made as follows : — Four hundred grains of chloral hydrate 

 being dissolved in about ten ounces of distilled water, sulphu- 

 retted hydrogen was passed through the solution till it possessed, 

 after being shaken, the odour of that gas. Sulphide of ammo- 

 nium was then added in small portions at a time, continuing 

 the passage of the sulphuretted hydrogen through the mixture, 

 when the effects before described were produced. This treat- 

 ment was continued till no further action appeared to take place, 

 and the mixture possessed, after being well shaken, a strong 

 odour of sulphuretted hydrogen. 



I may here observe that, after the addition of the sulphide of 

 ammonium, the evolution of ammonia was from the first percep- 

 tible, whilst the odour of the sulphide and of the gas for some 

 time continually disappeared, and it was not till the later stages 

 of the process that the smell of chloroform could be detected. 



To the mixture so treated, which was distinctly alkaline, pure 

 diluted sulphuric acid was added till it acquired an acid reaction, 

 and the whole was thrown on a filter, when the brown solid was 

 separated from a deep amber-coloured liquid. The former was 

 then washed with cold distilled water till no indication of sul- 

 phuric acid in the filtrate could be detected by chloride of barium; 

 but finding that it exhibited traces of ammonia when treated with 

 caustic lime, the washing of the brown solid was continued, first 

 using cold distilled water; and this failing to accomplish the 

 object sought, it was washed with a considerable quantity of hot 



