234 DR. E. SCHUNCK ON ANTHRAFLAVIC ACID. 



The formulae of the acid and its barium salt are there- 

 fore respectively Ci S H io 4 and C IS H 8 Ba0 4 -f- aq. It is 

 probable that the latter, when freshly crystallized, contains 

 some water of crystallization which is expelled at ioo°, in 

 addition to that which is retained at 120 C; but I made 

 no attempt to determine the amount. 



The silver salt also retains water with great pertinacity, 

 even when heated to a temperature of 140 C. The salt 

 was obtained as a reddish-brown precipitate by adding ni- 

 trate of silver to a solution of the acid in liquid ammonia. 



Its analysis led to the following results : — 



I. 0*4792 grm., dried at ioo° C, gave 0*6628 grm. car- 

 bonic acid and 0*0742 water. 



0*4836 grm. gave 0*2882 grm. chloride of silver. 



II. 0*3976 grm., dried at ioo° C, gave 0*1782 grm. silver. 



III. 0*4952 grm. silver salt of another preparation, dried 

 at 140 C, gave o*68 10 grm. carbonic acid and 0*0764 water. 



0*4924 grm. gave 0*2240 grm. silver. 



IV. 0*5484 grm., dried at 140 C, gave 0*7616 grm. 

 carbonic acid and 0*0810 water. 



0*4714 grm. gave 0*2132 grm. silver. 

 In 100 parts :— 



I. II. 



C 37*72 



H 172 



Ag 44*85 44"8i 



O 1571 



lOO'OO 



III. 



IV. 



37-50 



37-87 



171 



1*64 



45 '49 



45-22 



15-30 



15-27 



lOO'OO 



ioo-oo 



These numbers correspond with the formula 2C I5 H { 

 Ag 2 4 +aq. which requires in 100 parts : — 



c 37*73 



H 188 



Ag 45-28 



O 15-" 



IOO'00 



