414 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
forming- a yellovv solution, which deposits nothing on cooling, but on evaporation 
leaves a transparent dark yellow amorphous substance like resin, which remains soft 
for a long time, and only becomes hard and brittle after being heated in the water- 
bath for some time. This substance, when heated on platinum, burns with a yellow 
flame, leaving much charcoal. When heated in a tube, it melts and gives acid fumes 
and a yellow oily sublimate, in which on cooling some white crystals make their 
appearance. The alcoholic solution gives no precipitate with nitrate of silver, but 
the substance on being treated with boiling nitric acid is dissolved and decomposed, 
and nitrate of silver now gives an abundant precipitate. It is soluble in concentrated 
sulphuric acid with a brown colour, but on boiling the solution no sulphurous acid is 
evolved. Caustic soda dissolves it easily with a brown colour. On being analysed it 
yielded the following results: — 
0-3910 grm., dried in the water-bath, gave 0 6675 carbonic acid and O-flOO water. 
0'4055 grm. gave 0-4990 chloride of silver. 
In 100 parts it contained therefore — 
Carbon 46-55 
Hydrogen . . . . 3-12 
Chlorine .... 30-42 
Oxygen 19-91 
Since the carbon here is to the chlorine as 32C:3|C1, this substance must either 
have been a mixture, or it must have lost chlorine during the process of drying. 
Action of Caustic Alhalies on Chlororubian . — The action of alkalies on chlororubian 
differs essentially from that of acids. The chlorine in chlororubian is so loosely com- 
bined that the affinity of the alkaline metal is sufficient to remove it, and hence all 
the organic products of decomposition formed by the alkali are free from chlorine. 
If chlororubian be treated with a solution of caustic soda it dissolves easily, forming 
a red solution. If this solution be heated for some time, it deposits a quantity of 
dark reddish-brown flocks. When these flocks cease to be formed, the liquid, which 
is still red, is filtered, the flocks are washed with water until the excess of soda is 
removed, and they are then treated with boiling muriatic acid, by which their colour 
is changed to yellowish brown. After being collected on a filter and washed with 
water, they are then treated with boiling alcohol, in which they are but little soluble, 
placed on a filter, washed with alcohol and dried. After drying, there is obtained a 
yellowish-brown powder which has the following properties. It is almost insoluble 
both in alcohol and in caustic alkalies, though the latter impart to it a dark reddish- 
brown colour. It is not dissolved by hydrosulphate of ammonia. It contains no 
chlorine. When heated in a tube it gives a yellow crystalline sublimate, which 
dissolves easily in caustic alkalies. Its composition was determined by the following 
analyses : — 
I. 0-3980 grm., dried at 100° C. and burnt with chromate of lead, gave T0330 car- 
bonic acid and 0-1390 water. 
