=250. Calculation from Data obtained with Copper Carbonate.=—The wide variations observed in different methods of calculations in the preceding paragraph, are due in part to the different degrees of oxidation exerted on alkaline copper tartrate by the dextrose and levulose. Better results are obtained by conducting the analytical work with Ost’s modification of Soldaini’s solution (=128=). The relative quantities of levulose and dextrose oxidized by this solution are almost identical, and the calculations, therefore, result in nearly the same data, whether made from the numbers obtained with the residual dextrose or from the levulose destroyed. The method of applying this method is illustrated in the following calculation. _Example._—In a mixture of sucrose, invert sugar, and dextrose, the quantities of copper obtained by using the copper carbonate solution were as follows: Copper obtained before inversion = _a_ = 150 milligrams. ” ” after ” = _b_ = 250 ” ” ” ” destroying lev’e = _d_ = 137.5 ” ” equivalent to inverted sucrose = _b_ - _a_ = _c_ = 100 ” ” ” ” levulose = _b_ - _d_ = _e_ = 112.5 ” {44.0 milligrams invert sugar. _a_ = 150 milligrams Cu = {45.3 ” dextrose. {42.5 ” levulose. _d_ = 137.5 ” ” = 41.55 ” dextrose. _c_ = 100 ” ” = 29.5 ” invert sugar = 28.025 sucrose. _e_ = 112.5 ” ” = 31.9 ” levulose. 14.75 milligrams of dextrose = 48.5 milligrams Cu. 14.75 ” ” levulose = 51.5 ” ” 137.5 - 48.5 = 89.0 milligrams Cu due to dextrose present before inversion. 89.0 milligrams Cu = 27 milligrams dextrose before inversion. 150.0 - 89.0 ” ” = 61.0 ” Cu due to levulose present before inversion. 61.0 ” ” = 17.8 ” levulose before inversion. 17.8 × 2 = 35.6 milligrams invert sugar present before inversion. 27.0 - 17.8 = 9.2 ” dextrose ” ” ” Again: 112.5 - 51.5 = 61.0 milligrams Cu due to levulose present before inversion. 61.0 milligrams Cu = 17.8 milligrams levulose. 17.8 ” levulose indicate 35.6 milligrams invert sugar. Dextrose in invert sugar before inversion = 17.8 milligrams. Total dextrose before inversion = 27.0 milligrams. Dextrose above amount required for invert sugar = 27.0 - 17.8 = 9.2 milligrams. The respective quantities of the three sugars in the solution are, therefore: Sucrose = 28.025 milligrams. Invert sugar = 35.6 ” Dextrose = 9.2 ”