CARBOHYDRATES. 193 



sulphuric acid, the pyromucic acid extracted by means 

 of ether. Its potassium salt is thrown down^when 

 alcoholic potassa is added to a solution of furfurol in 

 alcohol. Colorless laminae or needles, easily soluble in 

 water, especially in hot water and in alcohol. Fuses 

 at 134, and sublimes even at 100. Monobasic acid. 

 Is converted into a well crystallizing acid, mucobromic 

 acid C 4 H 2 Br 2 3 , by bromine in the presence of water; 

 carbonic anhydride and hydrobromic acid being formed 

 at the same time. 



Furfurol (Pyromucic aldehyde), C 5 H 4 2 , is formed 

 by the distillation of sugar and by the distillation of 

 bran with dilute sulphuric acid. Colorless oil, of a 

 peculiar odor, soluble in 12 parts water, easily in alco- 

 hol; specific gravity, 1.165; boiling point, 162. It 

 turns dark in contact with the air, and is converted 

 into a pitchy mass. It is oxidized by boiling with 

 water and silver oxide, forming pyromucic acid. Com- 

 bines with alkaline bisulphites, and yields with am- 

 monia, fiirfuramide (C 5 H^O) 3 N 2 , water being elimi- 

 nated. Colorless crystals, insoluble in water, soluble 

 in alcohol ; without basic properties. Turns brown 

 under the influence of light ; and, when heated to 120, 

 or when boiled with caustic potassa, it is converted 

 into a base of the same composition furfurin, which 

 crytallizes in small colorless prisms, but slightly solu- 

 ble in water, easily in alcohol, fusing under 100. 



D. CARBOHYDRATES. 



The so-called carbohydrates are derivatives of the 

 hexatomic alcohols C 6 II 8 (OIT) 6 . They may be divided 

 into three groups, according to their composition. 



1. Grape-sugar group, C 6 II 12 6 . The bodies be- 

 longing to this group are in all probability the first 

 aldehydes of the hexatomic alcohols, formed by the 

 oxidation of one group CH 2 .OH to CHO. They still 

 contain five alcoholic groups. 

 17 



