858 U. S. BUREAU OF CHEMISTRY NOTES. [J. F. I.

CLERGET-INVERTASE HYDROLYSIS CONSTANTS OF SUCROSE AND RAFFINOSE.

By H. S. Paine and R. T. Balch.

[ABSTRACT.]

THE Clerget-invertase hydrolysis constant of sucrose was determined. The relation between sucrose concentration and this constant is expressed by the equation, constant = I 3 I. I 7 + 0.073 c, where c is the number of g. of sucrose in IOO C.C.

The value 0.521, which shows negligible variation over a considerable range of concentration, was found for the ratio of polarization of raffinose after invertase hydrolysis to the original polarization. These values are applicable in enzymic analytical methods for the determination of sucrose and of sucrose and raffinose in mixture.

AUTOMATIC DEVICES FOR THE EXTRACTION OF POWDERED MATERIALS.

By S. Palkin and H. R. Watkins.

[ABSTRACT.]

Two automatic devices for the extraction of solid substances, particularly plant drugs, are described. One is an inexpensive, simple device, in which the extracting solvent is made to flow rapidly upward through the sample and is continuously filtered through a cotton filter device back into the heating vessel. Absence of a thimble and the upward flow of solvent keeps the powdered material loosely suspended. The circulation principle causes the solvent to flow through the whole mass of sample evenly with no stagnant central cores, as might be the case where a thimble is employed. The same extractor vessel or jacket may also be used for the liquid extractors previously described.

The other device, somewhat more complex, makes use of the pressure effect of the solvent vapors to produce continuous agi- tation of the suspended sample. Continuous filtration is effected in the same way that it is in the simple form. This apparatus is applicable to the extraction of liquids as well.

*Published in J. Am. Chenz. sot., 49, April, 1927, pp. ~oxg-1028. ‘Published in Ind. Ellg. Clzcm.. IQ, April, 1927, pp. 535-537.