Dr. Schunck on Rubian and its Products of Decomposition. 425 



Eqs. Calculated. Found. 



Carbon ... 12 72 44-44 43-84 



Hydrogen. . 10 10 6-17 6-23 



Oxygen. . . 10 80 49*39 49-93 



l62 100-00 10000 



On subjecting it, however, for some time longer to the same 

 temperature, it became very brown, and its analysis now showed 

 that it had absorbed oxygen. 



0-5820 grm. now gave 0-8745 carbonic acid and 0*3000 water. 

 In 100 parts it contained therefore — 



Carbon ...... 40-97 



Hydrogen . . . . .' 5-72 



Oxygen ...... 53-31 



On redissolving the remainder in water, it gave a brown solu- 

 tion, but on adding to the solution hydrated oxide of lead, the 

 brown portion was removed, while the solution became almost 

 colourless, and on evaporation over sulphuric acid left a yellow 

 syrup, the composition of which again corresponded with the 

 formula C^^ H^^ 0'^, as will be seen by the following analysis : — 



0-3710 grm. gave 0-5535 carbonic acid and 0-2135 water. 



In 100 parts :— 



Carbon 40-68 



Hydrogen ..... 6*39 

 Oxygen ...... 52*93 



Ruhiafine. — In my former papers on madder I have described 

 a substance which I called rubiacine, and which I prepared partly 

 from madder itself, and partly by the reduction of rubiacic acid 

 with sulphuretted hydrogen. Now rubiafine cannot be distin- 

 guished by any of its properties from rubiacine. It crystallizes 

 from its alcoholic solution in yellow glittering plates and needles, 

 which are sometimes arranged in star-shaped or fan-shaped 

 masses. By carefully heating it, it may be volatilized without 

 leaving much residue, forming a yellow sublimate of small 

 shining needles. It is but slightly soluble in boiling water. 

 It is not decomposed by boiling nitric acid or by concentrated 

 sulphuric acid, but merely dissolved by them. It dissolves in 

 caustic alkalies with a reddish-purple, and in carbonated alkalies 

 with a red colour. Its alcoholic solution gives with sugar of lead 

 a fine crimson precipitate, with acetate of copper an orange- 

 coloured precipitate. It dissolves in a solution of pernitrate of 

 iron with a dark brownish-purple colour. The solution, after 

 being boiled for some time, gives, on the addition of muriatic 

 acid, a yellow precipitate, which is rubiacic acid. These proper- 

 ties, it will be seen, belong also to rubiacine. Nevertheless the 



Phil Mag, S. 4. Vol. 5. No. 34. June 1853. 2 F 



