Sulphuretted Nitrogenous Compound. 249 



distilled water till the presence of ammonia could no longer be 

 discovered in the filtrate. The brown matter was subsequently 

 dried, first by exposure to the air on the filter at the ordinary 

 temperature, then at a very gentle heat, and afterwards by ex- 

 posing it for some time under a bell-glass to the drying influ- 

 ence of sulphuric acid. 



As I thought it more than probable that the substance, from 

 the way in which it had been procured, contained some free 

 sulphur (which was afterwards shown to be the case), a portion 

 of that which had been so dried was placed in a stoppered bottle 

 and digested for some days along with bisulphide of carbon ; the 

 mixture was then thrown on a filter, and washed with repeated 

 fresh portions of pure bisulphide till but a faint trace of residue 

 remained after the evaporation of a little of the filtrate; and this 

 seemed to be due, not to sulphur as at the first, but to the brown 

 compound being soluble to a very slight degree in the bisul- 

 phide. After this treatment the bisulphide was allowed to eva- 

 porate oft from the substance, when it was placed as before under 

 a bell-glass along with a vessel containing sulphuric acid, where 

 it remained for some days. Thinking, however, that it might 

 still not be perfectly dry, it was subsequently heated in a water- 

 bath or oven to about 212° F., when I found that a very slight 

 amount of moisture was expelled from it, accompanied by a pe- 

 culiar sulphurous smell; and as soon as it appeared to lose no 

 further weight by this temperature, it was placed in a well-stop- 

 pered bottle and reserved for examination. 



The substance so obtained, and in this dry condition, possesses 

 the following properties : it is an amorphous solid of a light 

 brown earthy appearance, is easily reducible to a state of impal- 

 pable powder, and has a specific gravity of about 1*62. When 

 gently heated on platinum -foil it evolves a very peculiar odour, 

 then blackens, partially fuses, and, taking fire, burns with a pur- 

 plish-coloured flame, emitting a faint odour of sulphurous acid, 

 whilst it leaves a large carbonaceous residue, which on the appli- 

 cation of a stronger heat ignites and slowly burns away. 



It is very slightly soluble in water, alcohol, bisulphide of car- 

 bon, and in ether, whilst it is almost insoluble in chloroform 

 and in benzol. It is, however, readily dissolved by solutions of 

 the caustic alkalies, and by those of the alkaline carbonates and 

 sulphides, forming dark brown or reddish-brown solutions, from 

 which it is again precipitated, apparently unchanged, by the ad- 

 dition of an acid in excess. It dissolves also in solutions of the 

 hydrate of lime and of baryta, and is soluble to some extent in 

 alkaline chlorides and iodides. 



As to the action of acids, when it was treated with concen- 

 trated sulphuric acid it acquired a darker colour, and dissolved, 



