282 NON-NITROGENOUS NEUTRAL BODIES. 



it undergoes the lactic, and subsequently the butyric fermen- 

 tation ; with common yeast it passes into the state of vinous 

 fermentation. Digested with concentrated nitric acid, it developes 

 nitric oxide gas, and is converted into oxalic and saccharic acids ; 

 while chlorine gas converts it into hydrochloric and saccharic acids. 

 When digested with dilute sulphuric acid, its solution does not so 

 rapidly become brown as that of cane-sugar, and it is only on eva- 

 poration that we observe the formation of a blackish brown residue; 

 but its solution, when boiled with potash, very quickly assumes a 

 fine brownish-red tint, and at the same time evolves a pungent, 

 sweetish odour ; it may be evaporated with lime-water without the 

 development of any brown colour, the lime arid the sugar forming 

 a syrupy compound with a bitter taste. On treating an aqueous 

 solution of glucose with caustic potash, and then adding a salt 

 of oxide of copper, no precipitate is formed, but the solution 

 assumes a beautiful azure tint : after some time, this gradually 

 changes to a green colour, and finally a red powder is deposited ; 

 if the fluid be boiled, it at once assumes a yellow tint, and sub- 

 oxide of copper is separated as a yellow or yellowish red powder. 

 Glucose is distinguished by its property of forming a beautiful 

 crystalline compound with chloride of sodium. 



Composition. According to the above formula, glucose consists 



of: 



Carbon 12 atoms .... 40'000 



Hydrogen .... 12 .... C'666 



Oxygen 12 .... 53-334 



100-000 



Its atomic weightz=2250. (Peligot,* Erdmann and Lehmann.f) 



Combinations. The compound of glucose and potash, 2KO + 

 C I2 H 12 O 12 , is obtained by adding an alcoholic solution of caustic 

 potash to an alcoholic solution of glucose ; it occurs in the form of 

 white floccuii which, on exposure to the air, soon become tenacious 

 and moist, and at length perfectly deliquescent ; when dissolved in 

 water they exhibit an alkaline reaction, and attract carbonic acid 

 from the atmosphere. 



The compound of glucose and lime, 2CaO -j-C 12 H 12 O 12 , is formed 

 when a solution of glucose is mixed with an excess of lime, and 

 the filtered fluid treated with alcohol ; it forms a white mass, which 

 on exposure to the atmosphere attracts water and becomes transpa- 

 rent. . 



It is not easy to obtain a combination of glucose with oxide of 



* Ann. do Ch. et de Phys. T. 60, p. 110, and Compt. rend. T. 6, p. 232. 

 t Journ. f. pr. Ch. Bd. 13, S. 113. 



