12 ATKINB: THE ANALYSIS OF HONEY THE ANALYSIS OF HONEY AND OTHER SUBSTANCES CONTAINING LJEVULOSE. BY W. R. G. ATKINS, Sc.D. (Red at the Meeting, December 6,1916.) IN the course of some work on mixtures of the three reducing sugars, dextrose bvulose, and maltose, met with in plant tissues, it was found necessary to devise means for the estimation of each. If maltose is hydrolysed by prolonged boiling with acid, so much laevulose is destroyed as to render the estimation worthlem The oxidising action of bromine in removing aldehydic sugars while leaving the ketonic sugar lzevulose untouched, was finally made use of for the purpose of estimat ing one constituent of the mixture of the three sugars. While the work was in progress the researches of Davis and Daish (ANALYST, 1913,38,504) were published These workers obtained very accurate results, but the preparation of cultures of pure yeasts is troublesome, and the length of time, about twenty-one days, required for complete fermentation is a drawback to the general usefulness of the method for technical analyses.The bromine method of Wilson and Atkins (ANALYST, 1917, 19) does not give as accurate results as those obtained by Davis and Daish, but it is rapid.If a mixture containing dextrose, laevulose, and maltose, to which has been added excess of bromine and enough sulphuric acid to render the solution deci- normal, be allowed to remain for forty-two hours at room temperature, the laevulose only is unoxidised. To insure completion of the reaction the reaction flask must be ahaken continuously during the period.This may be effected by causing it to rotate slowly with the long axis of the bottle a t a small angle to the horizontal Glms beads in the solution may also be used to assist shaking. The maltose leaves a mere trace of reducing power, dextrose leaves approximately 1 per- cent. of the original reducing power? and laevulose falls off in reducing power approximately 1 to 2 per cent., owing to its decomposition, even in the cold, by the & acid i n d by the hydrobromic acid formed during the oxidation of the other pugare The slight loss in the quantity of laevulose is roughly balanced by the reducing power remaining after the destruction of the dextrot3e and maltose. The excess o bromine is cautiously removed by gaseous sulphur dioxide, and finally by titratio] with dolution of t,he gas in water.The acidity is just removed by the addition o potassium carbonate, care being taken to leave the liquid neutral or faintly acid, bu not alkaline. Fo this we found Kendall’s solution (ANALYST, 1912,37, 205) suitable, as it does no dissolve the cuprous oxide. Kendall did not give a, table for laevulose, so one wa constructed by the author (ANALYST, 1916,41,285).By this means laevulose may be estimated readily and with tolerable accurac in the presbnce of dextrose and maltose, or either of them. If only dextrose an lmvulose are pregent, as in natural honey, which contains about 36 per cent. of th latter, it is sufficient to determine the reducing power before and after oxidatio The reducing power of an aliquot portion is then determined.AND OTHER SUBSTAXCES CONTAINING LLEVUJIQSE 13 with bromine. The cane-sugar in the honey musf be estimated separately by determining the reducing power before and after inversion.Oxidation should be effected on the inverted solution, due allowance being afterwards made for the dextrose and laevu1,ose resulting from the inversion.It is, of course, possible to estimate dextrose and lsvulose in a mixture of the two by obtaining the total reducing power and the optical activity. From these data, two equations can be constructed, and a solution of the simultaneous equations gives the values of each. In this procedure, however, errors are magniiied, and the procedure is not so accurate as the determination of reducing power before and after oxidation. It appears that oxidation with bromine may be of use in the technical analysis of honey, syrups, jams, and other articles containing these sugars, especially as it affords an easy method of detecting the presence of dextrose in abnormal quantities. TRINITY COLLEQE, DUBLIN.