812 EXPERIMENT STATION RECORD. 



method of determining sucrose], V. Stanek {Ztsclir. Zuckerindus. Bohmen, 

 37 {1912), No. 1, pp. 1-17; als. in Jour. 8oc. Chem. Indus., 31 {1912), No. 20, 

 p. 1001). — In the experiments solutions of potassium glutamate were heated in 

 sealed tubes for periods varying from one-half to 24 hours and to temperatures 

 from 90 to 250° C, when the rotation in the presence of basic lead acetate and 

 hydrochloric acid was determined. Heating at a low temperature and for a 

 comparatively short time almost destroyed the optical activity. 



" On studying the products of decomposition thus obtained, it was found that 

 levorotatory glutimic acid, C5H7XO3, is formed at the lower temperatures, such 

 in fact as are used in practice, but that above 200° the optically inactive iso- 

 merid of the same acid is almost exclusively proved. In presence of hydro- 

 chloric acid, even in the cold, it was noticed that the optically active isomerid 

 gradually loses its levorotation and becomes dextrorotatory, finally, in fact, 

 becoming hydrolyzed to glutamic acid hydrochlorid, CsHsXOiHCl. This obser- 

 vation has an important bearing on the determination of sucrose by the double 

 polarization method in beet products, and it is computed by the author that if 

 only 3 per cent of the levorotatory glutimic acid be present in beet molasses, 

 the error will be 0.9 per cent when the ordinary basic lead acetate direct read- 

 ing is followed; but only about 0.05 per cent if the acid direct polarization, 

 using hydrochloric acid and urea, be employed." 



A revision of the hundred point of the saccharimeter, F. J. Bates and 

 R. F. Jackson {Orig. Commun. 8. Internet. Cong. Appl. Chem. {Washington 

 mid Neiv Yoy-k], 25 {1912), Sects. I-Ve, p. 517). — "For the purpose of checking 

 the accuracy of saccharimetric analysis, the polarization of highly purified 

 sugar solutions was measured. For the preparation of pure sucrose the method 

 of crystallization from aqueous solutions after concentration in a vacuum 

 boiling apparatus was developed. The sugar thus prepared did not differ 

 essentially from that precipitated by alcohol. A study of the purified sugar 

 showed the absence of ash and a negligible quantity of reducing substances. 



" The experiments on reducing sugars showed the effect of sucrose on alkaline 

 copper solutions and in the calculations this effect was taken into considera- 

 tion. The velocities of caramelization of sugar at various temperatures were 

 measured and a curve platted indicating the length of time needed at each 

 temperature to produce a quantity of caramel equivalent in reducing power to 

 0.01 per cent invert sugar. The data are for 79.5°, 1.8 hours ; 66.6°, 10.9 hours ; 

 50°, 107 hours; 39°, 478 hours. 



" The results prove that caramelization occurs at comparatively low tem- 

 peratures, the effect taking place spontaneously, if slowly, at laboratory tem- 

 peratures. The allowable time of heating as determined by the caramelization 

 curve was applied to moisture elimination. A combination of high temperature 

 and high vacuum was relied upon to dry the sample. Solutions for polarization 

 were prepared, both gravimetrically, by reference to density tables, and volu- 

 metrically. The specific rotation of the normal solution was measured on a 

 precision polarimeter for wave length 546.1 and found to be 78.385° at 20° C. 

 By the use of a quartz plate, which had been certified by the Physikalisch- 

 Technische Reichsanstalt and the Bureau of Standards, the scale correction of 

 a saccharimeter was found and the correction applied to the polarization of the 

 normal sugar solutions. These latter read not 100° but 99.91. The Herzfeld- 

 Schonrock standard was concluded to be in error. If so, the new conversion 

 factor for X=:589.25 was computed to be 34.626, and that for X=546.1 was 

 40.707." 



About the determination of raffinose in the sug'ar beet, L. Nowakowskt 

 and J. MuszYNSKi {Ahs. m Centbl. Zuckerindus., 21 {1913), No. 48, p. 17^8). — 

 The methols used for determining raflanose at the present time depend upon 



