Dr. Schunck on Rubian and its Products of Decomposition. 513 



more manifest proof of tlie fact of purpurine not being a substance 

 of uniform composition, is derived from an examination of the 

 liquid from which these specimens were deposited. To the bright 

 red liquid from which the last was deposited, I added after fil- 

 tration muriatic acid and boiled. A yellow precipitate was pro- 

 duced, which was collected on a filter and washed. A small quan- 

 tity of it being dissolved in alcohol, the alcohol left on evapora- 

 tion crystals of apparently pure alizarine. Its analysis also 

 showed that it consisted of alizarine almost in a state of purity. 

 0-2390 grm. gave 0-6040 carbonic acid and 00980 water. 

 In 100 parts it contained therefore — 



Alizarine. 

 Carbon .... 68-92 69-42 



Hydrogen ... 4*55 4-13 



Oxygen .... 26-53 26-45 



I now prepared some so-called purpurine from garancine. 

 The garancine was treated with boiling alum liquor, and the 

 liquor was strained boiling hot through calico. On cooling there 

 was formed a copious deposit, which was redissolved in fresh 

 alum liquor. The deposit formed this time, which was very 

 trifling, was separated, and the substance contained in the liquid 

 was precipitated with muriatic acid. The precipitate was yellow. 

 Its analysis proved it to be almost pure verantine. 



0-3685 grm. gave 0-8760 carbonic acid and 0-1400 water. 

 In 100 parts it contained therefc^e — 



Verantine. 

 Carbon .... 64-83 65-11 



Hydrogen ... 4-22 3-87 



Oxygen .... 30*95 31-02 



It appears therefore that the substance called purpurine cannot 

 even be called a compound of alizarine and verantine, for it 

 consists sometimes of one alone, sometimes of the other, some- 

 times of a variable mixture of both. 



I now treated some purpurine, made in the same manner as 

 the last, with boiling dilute nitric acid. Nitrous acid was disen- 

 gaged, the bulk of the substance diminished very much, and its 

 colour became lighter. After the action was completed, I 

 allowed the liquid to cool, added water, collected the yellow 

 flocks on a filter, and washed them with water to remove all the 

 acid. After drying their colour was brownish-yellow, similar to 

 that of pure verantine. 



0-3820 grm. gave 0-9070 carbonic acid and 0-1240 water. 

 In 100 parts — 



Carbon 64-72 



Hydrogen 3*60 



Oxygen 31-68 



