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



the substance on being treated with boiling nitric acid is dis- 

 solved and decomposed, and nitrate of silver now gives an abun- 

 dant 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 0*1 100 water. 



0'4055 grm. gave 0*4990 chloride of silver. 



In 100 parts it contained therelbrer-i^ 



Since the carbon here is to the chlorine as 32 C : 3J CI, this 

 substance must either have been a mixture, or it must have lost 

 chlorine during the process of drying. 



Action of Caustic Alkalies on Chlororubian. — The action of 

 alkalies on chlororubian differs essentially from that of acids. 

 The chlorine in chlororubian is so loosely combined that the 

 aflSuity 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 dis- 

 solves 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 fol- 

 lowing 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 yel- 

 low 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 10330 carbonic acid and 0*1390 water. 

 J.. II. 0*3910 grm. gave 10150 carbonic acid and 0*1370 water. 



III. 0-4000 grm. of a new preparation gave^l*0350 carbonic 

 acid and 0*1435 water. 



