Dr. Schunck on Rubian and its Products of Decomposition. 415 



Hence may be deduced the following composition : — 



Eqs. Calculated. I. II. 



Carbon. . . 12 72 3017 2941 3001 



Hydrogen . . 10 10 4-19 468 4*62 



Oxygen. . . 10 80 33-54 33-49 



Baryta ... 1 76'6 32-10 31-88 



238-6 10000 100-00 



This compound, it will be seen, is identical in composition 

 with the baryta compound of cane-sugar. If the formulae of 

 the two compounds be compared together, it is evident that if 

 both be correct, the one containing most baryta must be written 

 thus,— C12 WO Qio ^ BaO + BaO HO. In this case, however, it 

 would be difficult to conceive how it is possible for the second 

 atom of baryta to escape the action of the carbonic acid used in 

 its preparation. It is therefore more probable that the true for- 

 mula is Ci2HioOio + 2BaO, which requires in 100 parts,— 



Carbon 22-84 



Hydrogen 3-17 



Oxygen 2539 



Baryta 48-60 



In fact the amount of carbon and hydrogen found by expe- 

 riment agrees better with these numbers than with those of the 

 other formula. 



These analyses lead to the conclusion, that the sugar formed 

 by the decomposition of rubian contains 12, not 14 atoms of 

 carbon. Nevertheless it is doubtful whether in these baryta 

 compounds the sugar exists in the same state as it does when 

 formed by the action of acids on rubian. In the latter state it 

 seems incapable of entering into combination with bases such as 

 baryta or oxide of lead. It is therefore probable that by the 

 continued action on it of alkalies or alkaline earths it undergoes 

 some change, possibly in consequence of the loss of the elements 

 of water. 



Among the products of the action of alkalies on rubian, I have 

 mentioned a dark brown substance insoluble in boiling alcohol. 

 This substance is soluble in alkalies with a brown colour, and 

 is reprecipitated by acids. It resembles in all respects the black 

 substances bearing the general name of humus, which are formed 

 by the action of strong acids and alkalies on ordinary sugar. It 

 was analysed with the following result : — 



0*3215 grm. gave 0*8040 carbonic acid and 0-1260 water. 



In 100 parts therefore it contains — 



Carbon 68*20 



Hydrogen 4*35 



Oxygen 27*45 



