80 Society for Experimental Biology and Medicine. 



Levulose, 0-583 volts. 

 Galactose, 0.562 " 



Glucose, - 0.558 " 

 Maltose, 0.532 11 

 Lactose, 0.519 " 



The constancy of the decomposition tension shows that in solu- 

 tions containing different concentrations of cupric acetate but hav- 

 ing the same rate of oxidation of any single sugar, the product of 

 the concentration of the cupric ions and the oxygen ions is a con- 

 stant, or C Cu -+ x C5 = K. The fact that for the same rate of 

 oxidation of the different sugars this product varies, shows that 

 the per cent, of dissociation into reactive products of the different 

 sugars also varies and in fact that levulose dissociates most, then 

 galactose, glucose, maltose and lactose in a diminishing order. 

 Preliminary observations indicate that for the same rate of oxida- 

 tion, the product of Cux O x dissociated sugar molecules is a 

 constant 



The oxidizing potential of all solutions containing cupric ions 

 appears to be constant ; these solutions differ only in their rates of 

 oxidation. Acid cupric sulphate is reduced by glucose, levulose, 

 etc., but at a very slow rate. The constancy depends on the con- 

 stant ionic potential of the cupric ions, regardless of their concen- 

 tration. This potential is 0.668 volt. Fehling's solution differs 

 from a cupric acetate-acetic acid solution not in its potential but 

 only in its speed of oxidation. The superior speed of action of a 

 Fehling's solution over a cupric acetate solution is due to the 

 enormously greater concentration of oxygen ions (hydroxyl ions) 

 in the Fehling's solution and also to the fact that the dissociation 

 of the sugar molecule into active particles is enormously greater in 

 an alkaline than an acid medium. (Schade : Zeitschrift fur physikal. 

 Client ., 1906, lvii, pp. 1-46. Nef's work on glycols, etc.) 



These facts show why it is that the sugars are oxidized and 

 fermented by the tissues, by moulds and bacteria at different rates, 

 this being due to the greater dissociation of certain sugars. A 

 cupric acetate-acetic mixture of proper concentration will show the 

 same selective action toward levulose that many bacteria and other 

 living organisms show and oxidize the levulose almost completely 

 before the glucose is attacked. Whether sugars differ also among 

 themselves in their reducing potential has not yet been determined. 

 No indications of such a difference have as yet occurred to us. 



