A solution of the carbohydrate is prepared containing a known weight of the substance in 100 cubic centimeters of water. About 120 cubic centimeters of the solution are introduced into a thin beaker of about 400 capacity. This beaker is closed with a stopper with three holes. Through one of these a glass rod for stirring the solution is inserted. The second perforation carries a delicate thermometer graduated to 0°.05. The temperature is read with a telescope. The beaker is placed in a mixture of ice and brine at a temperature from 2° to 3° below the freezing point of the solution. The solution is cooled until its temperature is from 0°.5 to 1° below the point of congelation. Through the third aperture in the stopper a small lump of ice taken from a frozen portion of the same solution, is dropped, causing at once the freezing process to begin. The liquid is briskly stirred and as the congelation goes on the temperature rises and finally becomes constant. The reading is then taken. The depression in the freezing point, controlled by the strength of the solution, should never be more than from 1° to 2°. The molecular weights may also be determined by the boiling points of their solutions as indicated by the author,[118] Beckmann,[119] Hite, Orndorff and Cameron.[120] The method applied to some of the more important carbohydrates gave the following results: DEXTROSE. Calculated for C₆H₁₂O₆. Found. _M_ = 180 _M_ = 180.2 SUCROSE. Calculated for C₁₂H₂₂O₁₁. Found. _M_ = 342 _M_ = 337.5 INVERTOSE (DEXTROSE AND LEVULOSE). Calculated for C₆H₁₂O₆. Found. _M_ = 180 _M_ = 174.3 MALTOSE. Calculated for C₁₂H₂₂O₁₁. Found. _M_ = 342 _M_ = 322 LACTOSE. Calculated for C₁₂H₂₂O₁₁. Found. _M_ = 342 _M_ = 345 ARABINOSE. Calculated for C₅H₁₀O₅. Found. _M_ = 150 _M_ = 150.3 RAFFINOSE. Calculated for C₁₈H₃₂O₁₆.5H₂O. Found. _M_ = 594 _M_ = 528 =149. Birotation.=—As is well known, dextrose exhibits in fresh solutions the phenomenon of birotation. The authors supposed that this phenomenon might have some relation to the size of the molecule. They, therefore, determined the molecular volume of freshly dissolved dextrose by the method of Raoult and found _M_ = 180. The high rotatory power of recently dissolved dextrose is therefore not due to any variation in the size of its molecule.