_p_ = grams in 100 [_a_]_{D}20° calculated for grams of solution. anhydrous dextrose. 7.6819 52°.89 9.2994 52°.94 9.3712 52°.94 10.0614 52°.96 10.6279 52°.98 12.9508 53°.05 18.6211 53°.25 31.6139 53°.83 40.7432 54°.34 43.9883 54°.54 53.0231 55°.17 82.6111 57°.80 =107. Gyrodynats of Other Sugars.=—Of the other sugars it will be sufficient to mention only levulose, maltose, lactose, and raffinose. For complete tables of gyrodynatic powers the standard books on carbohydrates may be consulted.[69] The gyrodynat of levulose is not definitely established. At 14° the number is nearly expressed by [_a_]_{D}14° = -93°.7. Invert sugar, which should consist of exactly equal molecules of dextrose and levulose, has a gyrodynat expressed by the formula [_a_]_{D}0° = -27°.9, with a concentration equivalent to 17.21 grams of sugar in 100 cubic centimeters. The gyrodynat decreases with increase of temperature, according to the formula [_a_]_{D}_t_° = -(27°.9 - 0.32_t_°). According to this formula the solution is neutral to polarized light at 87°.2, and this corresponds closely to the data of experiment. Maltose, in a ten per cent solution at 20°, shows a gyrodynat of [_a_]_{D}20° = 138°.3. The general formula for other degrees of concentration is [_a_]_{D} = 140°.375 - 0.01837_p_ - 0.095_t_, in which _p_ represents the number of grams in 100 grams of the solution and _t_ the temperature of observation. In the case of lactose [_a_]_{D} = 52°.53, and this number does not appear to be greatly influenced by the degree of concentration; but is somewhat diminished by a rising temperature. The gyrodynat of raffinose in a ten per cent solution is [_a_]_{D} = 104°.5. CHEMICAL METHODS OF ESTIMATING SUGARS.