4-'J0 Mr. Thomas Richardson on Doniinn, a 



The green precipitate thrown down hy sulpho-hydrate of 

 ammonia, was thus separated into three portions : 



A. That which was dissolved in caustic ammonia. 



B. That which was dissolved in caustic soda. 



C. The undissolved brown portion, which was separated 

 from the caustic soda solution. 



A. The caustic ammonia solution was evaporated to dry- 

 ness, and the dry mass heated to redness in a platinum cap- 

 sule. The residue was a very light white powder, which 

 possessed the following characters : 



I. Before the blowpipe. 

 Per se. It is not altered. 



With carbonate of soda in the exterior flame, it tinges 

 the bead of a green colour, which changes to pink in the 

 interior. 



With borax, it fuses into a transparent colourless bead. 



With salt of phosphorus it fuses into a transparent bead, 

 which is yellowish while hot, but which becomes colour- 

 less on cooling. 



With nitre in the exterior flame, it forms a mass of a blue 

 colour, which undergoes no change in the interior. 



With a solution of nitrate of cobalt, the substance is 

 tinged of a purple colour, which is very deep at first. 



II. This white substance dissolves in nitric and muriatic 

 acid, and with difficulty in sulphuric. 



III. The solution in muriatic acid, concentrated and set 

 aside, deposited very minute crystals, which appeared to 

 be four-sided prisms, and when evaporated to dryness, the 

 residual fall had a bright yellow colour, a sweet astringent 

 taste, and deliquesced when exposed to the air. 



IV. The same solution slightly acid, behaved in the fol- 

 lowing manner with re-agents : — 



1 . With caustic ammonia — gave a white flocky preci- 

 pitate, soluble in excess of the precipitant. 



2. With caustic soda — it acted in the same way. 



3. With carbonate of ammonia — also in the same way. 



4. With carbonate of soda — white flocky precipitate, 

 insoluble in excess of re-agent. 



5. Sulpho-hydrate of ammonia — flocky green precipitate. 



6. Oxalate of ammonia — no precipitate. 



7. Phosphate of ammonia — curdy white precipitate. 



