282 Dr. Schunck on Rubian and its Products of Decomposition. 



little animal charcoal may be added. On filtering boiling hot 

 and allowing to cool, the solution then yields perfectly colour- 

 less crystals. It may also be obtained directly from rubian, by 

 continuing to pass chlorine through a watery solution of the 

 latter, uutil the yellow precipitate produced at first has become 

 white, but by this means it is not obtained as pure as from cry- 

 stallized chlororubian. 



Perchlororubian has the following properties. When heated 

 on platinum it melts to a brown liquid, and then burns with a 

 smoky yellow flame edged with green, leaving little carbonaceous 

 residue. If slowly and carefully heated it may be entirely vola- 

 tilized, yielding a sublimate of bright micaceous scales. But if 

 it be suddenly heated, if, for instance, it be thrown into a red- 

 hot tube, it is decomposed with a kind of explosion, giving off 

 an acid smell, and forming a large quantity of soot with little or 

 no crystalline sublimate. It is insoluble in water, but soluble 

 in alcohol and aether. The alcoholic solution does not redden 

 litmus paper. Concentrated sulphuric acid dissolves it on heat- 

 ing, the solution, on being heated to the boiling-point, becoming 

 slightly brown, but giving off very little sulphurous acid. The 

 colder parts of the tube become covered with a crystalline sub- 

 limate, consisting probably of the substance itself. Nitric acid 

 of sp. gr. 1*37 has no effect on it, even on boiling. Nitric acid 

 of sp. gr. 1'52 dissolves it on boiling without decomposing it, 

 for on adding water, the substance is precipitated unchanged in 

 the shape of a crystalline deposit, and nitrate of silver produces 

 in the liquid no precipitate of chloride of silver. Perchlororubian 

 is quite insoluble in strong caustic soda lye, even on boiling, as 

 well as in ammonia. - It dissolves easily, however, in hydrosul- 

 phate of ammonia on boiling, and on now adding nitric acid and 

 boiling, nitrate of silver produces an abundant precipitate. The 

 alcoholic solution gives no precipitate with an alcoholic solution 

 of acetate of lead. Its analysis led to the following results : — 



I. 0*4945 grm., dried at 100° C. and burnt ^with chromate 

 of lead, gave 0*6730 carbonic acid and 0*0610 water. 



0*4350 grm., burnt with lime, gave 0-7770 chloride of silver. 



II. 0*3930 grm. of another preparation gave 0*5330 carbonic 

 acid and 00585 water. 



0*2730 grm. gave 0*4930 chloride of silver. 

 These numbers lead to the following composition :- 



711-6 10000 10000 10000 



