26 Dr Fenton, A Delicate Reaction for Carbohydrates. 
dextrins, cellulose in different forms, salicin, amygdalin, and the 
mixture of sugars resulting from the condensation of glycollic 
aldehyde. 
No indication was given by arabinose, xylose, glycollic alde- 
hyde, mannitol, erythritol, glycerol, gluconic acid, mucic acid or 
inosite. 
It appears, therefore, that this test may be used for the 
identification of all hexoses or of other carbohydrates, glucosides, 
&c. which yield hexoses on hydrolysis. 
The test appears to possess some advantages over most of 
the usual colour-reactions for carbohydrates in that the effect is 
restricted to the hexose, or polyhexose, nucleus. The fluorescent 
character of the solution, moreover, is a property which is less 
liable to be mistaken than is the mere shade of colour upon which 
many of the other tests depend. 
It is possible that this reaction may be found serviceable in 
demonstrating the existence of hexose residues in complex natural 
products, such as proteid substances. 
Addendum, Jan. 8, 1907. 
Later experiments have shewn that this test may even be 
applied to the detection of sugars in dilute aqueous solution if 
the following modification is adopted : — 
About 2 or 3 c.c. of the solution is poured on to an excess of 
solid calcium chloride, so as to make a semi-solid mass; about 
10 c.c. of toluene, containing two or three drops of phosphorus 
tribromide, is then added and the mixture is heated to boiling 
for a few minutes. About 1 c.c. of malonic ester and a little 
alcohol are then introduced and the mixture is made just alkaline 
with alcoholic potash. At this point a characteristic pink colour 
is usually observed. Excess of alcohol and a few drops of water 
are then added, when the blue fluorescence becomes apparent, 
either immediately, or after standing for a minute or two. 
