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XLIX. Note on Inverted Sugar. By James Dewar, F.R.S.E., 



Chemical Demonstrator in the University, Lecturer on Chemistry, 

 Veterinary College, Edinburgh*. 



FOR some time past an animated discussion has been going 

 on in the columns of the Comptes Rendus de V Academie 

 des Sciences between MM. Dubranfaut and Maumene regarding 

 the nature of inverted sugar. M. Dubranfaut, many years ago, 

 made many valuable additions to our knowledge concerning the 

 composition and reactions of various sugars, especially in explain- 

 ing the result of the action of dilute acids on cane-sugar. He 

 explained the lsevo-rotatory action of inverted sugar, and its ra- 

 pidly varying power with the temperature, as the result of a 

 molecule of water in reacting with a molecule of cane-sugar, ge- 

 nerating one molecule of glucose and one of lsevulose. Dubran- 

 faut believed that inverted sugar consisted of a mixture of glucose 

 and lsevulose in equal weights ; and although he did not make a 

 direct analysis of the product, yet he was justly entitled to assume 

 that it was so constituted, seeing that generally it agreed with a 

 mean of the properties of inulin sugar and dextrose. 



In order to support the above view, he separated lsevo-glucose 

 from the inverted sugar, through the insolubility of the lime 

 compound, and compared its properties with pure lsevulose. The 

 decomposition would, according to Dubranfaut, be as follows : — 



C" H 22 O 11 + H 2 = C 6 H 12 6 + C 6 H 12 O 6 

 + 73-8 +56 -106 



(-25) 



So thoroughly had his facts and explanations been accepted 

 by chemists generally, that, up to a recent date, no one disco- 

 vered any flaw in his researches, and therefore no doubt was 

 thrown on the validity of thist heory. Recently Maumene has 

 reinvestigated the composition of inverted sugar by analysis. 

 He has attempted to separate the two sugars through the action 

 of chloride of sodium. The dextro-glucose forms a well-defined 

 crystalline compound with chloride of sodium, whereas the lse- 

 vulose does not form any compound. The results obtained by 

 this method differ greatly from theory. Instead of finding 50 

 per cent, of lsevulose, he found 88 per cent. In repeating the 

 experiments of Dubranfaut on the separation of lsevo-glucose by 

 hydrate of lime, he has not met with any better results ; in fact 

 his results are quite opposed to those of Dubranfaut. 



Apart altogether from expressing an opinion on the merits of 



* From the Proceedings of the Royal Society of Edinburgh, Session 

 1869-70. Communicated by the Author. 



