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



Sugar. — That the substance obtained from the acid liquid after 

 the complete decomposition of rubian is a species of sugar, will, 

 I think, be apparent from an enumeration of its properties. It 

 is always obtained in the form of a transparent yellow syrup, 

 which neither crystallizes, however long its solution may be left 

 to stand, nor becomes dry, unless heated to 100° C. Its taste 

 is sweetish, accompanied by a bitter after-taste, like that of burnt 

 sugar. When heated for some time at 100° C. it loses a por- 

 tion of its water, but remains soft and viscid. On allowing it 

 however to cool, it becomes brittle and capable of pulveriza- 

 tion. After a few moments' exposure to the air it again begins 

 to attract moisture, which it does as rapidly as chloride of cal- 

 cium, and is soon reconverted into syrup. This is a character 

 which it has, in common with ordinary syrup, obtained by boil- 

 ing a solution of cane-sugar in water. It is soluble in alcohol. 

 It is not affected by dilute sulphuric acid, even on boiling ; but 

 on evaporating a solution to which sulphuric acid has been 

 added, it is decomposed in proportion as the acid becomes con- 

 centrated, and is changed into a black powder like humus. Con- 

 centrated sulphuric acid destroys it immediately with disengage- 

 ment of sulphurous acid. It is destroyed by nitric acid. By 

 operating on a moderately large quantity of it, I was enabled to 

 ascertain that the sole product of the action of nitric acid is 

 oxalic acid. It is not precipitated from its watery solution by 

 any metallic or other salt, not even by basic acetate of lead. 

 On the addition of caustic potash or soda to its solution and 

 boiling, the solution immediately becomes brown, and a brown 

 powder falls, just as in the case of grape-sugar. It is capable 

 of fermentation. The watery solution when mixed with yeast 

 soon begins to ferment, though the process is not so lively as 

 in the case of an equal quantity of common sugar; and by 

 distilling the liquid and boiling the distillate with dry carbonate 

 of soda, alcohol may be obtained. 



The analysis was attended with some difficulty on account of 

 the great affinity which it has for water. By heating it however 

 for some time at 100° C, then allowing to cool and pulverizing 

 while in its brittle state as quickly as possible, it was obtained 

 in a condition fit for analysis. Even then however the state of 

 hydration was not uniform, so that the analyses differed consi- 

 derably from one another. The following results were ob- 

 tained : — 



I. 0*4765 grm., burnt with chromate of lead, gave 0-6860 

 carbonic acid and 02905 water. 



II. 0-3050 grm. gave 0-4450 carbonic acid and 0*1 815 water. 



III. 0-3820 grm. gave 05650 carbonic acid and 0-2205 water. 

 These numbers give in 100 parts — 



