500 Dr. Schunck on Ruhian and its Products of Decomposition. 



addition of sulphuric acid and water a yellow powder, which was 

 collected on a filter, washed, dried and weighed. It was then 

 treated with a little cold alcohol. This left undissolved a quan- 

 tity of rubiagine, which was again collected on a filter, dried and 

 weighed. The alcohol left on evaporation a dark brown mass, 

 the fatty nature of which showed that it contained rubiadipine 

 in addition to rubiretine. Now I obtained from that half of the 

 solution to which carbonate of soda had been added, the follow- 

 ing quantities of these various substances : — 0*323 grm. alizarine, 

 0*220 grm. rubiafine, 0*167 grm. of the mixture of rubiafine and 

 verantine, 0*250 grm. rubiagine, and 0*170 grm. of the mixture of 

 rubiretine and rubiadipine. From the other half, to which sulphuric 

 acid had been added, I obtained the following quantities of the same 

 bodies : — 0*2030 grm. alizarine, 0*340 grm. rubiafine, 0*157 grm. 

 of the mixture of rubiafine and verantine, 0*310 grm. rubiagine, 

 and 0*230 grm. of the mixture of rubiretine and rubiadipine. In 

 both cases a quantity of rubian remained undecomposed, but the 

 quantity actually decomposed was capable of being approximately 

 determined from the quantities of products of decomposition 

 formed. Assuming the formula of rubiafine to be C^^H^^O^, 

 that of rubiagine C^^H*'*0^^, assuming further that the mixture 

 of rubiafine and verantine consisted entirely of the latter sub- 

 stance, by which no great error is committed (since the quanti- 

 ties of rubiafine and verantine which one atom of rubian is capable 

 of yielding are to one another as 277 to 258), and leaving out 

 of consideration the trifling quantity of rubiadipine formed (the 

 rubiretine being given by the amount of verantine), then the 

 quantities of the various substances obtained correspond respect- 

 ively to the following quantities of rubian : — 



Rubian. Rubian. 



Alizarine . 0*323 corresp. to 0*407 0*203 corresp. to 0*255 

 Rubiafine . 0*220 corresp. to 0*484 0*340 corresp. to 0*748 

 Rubiagine 0*250 corresp. to 0*533 0*310 corresp. to 0*661 

 Verantine . 0*167 corresp. to 0*394 0*157 corresp. to 0*371 



T8l8 "2035 



Hence it appears that though the amount of rubian which 

 actually underwent decomposition was less when carbonate of 

 soda was added than when sulphuric acid was employed in addi- 

 tion to the ferment, still the amount of the alizarine produced 

 was greater in the former than the latter case, while the amount 

 of almost all the other substances was proportionally less. In 

 using carbonate of soda, the quantity of alizarine formed amounted 

 to 1 7'7 per cent., in using sulphuric acid it amounted to 9*5 per 

 cent, of the rubian decomposed. The quantity which should be 

 formed, if the rubian were entirely converted into alizarine, is 

 79*3 per cent. 



