August 5, 1921] 



SCIENCE 



117 



The effect of varying hydrogen-ion concentra- 

 tion upon the decolorization of cane juice with 

 carbon: J. F. Brewster and W. G. Raines. 



Tlie effect of some decolorizing carbons on the 

 color and colloids of cane juice: J. F. Brewster 

 and W. G. Raines. 



The determination of color and decolorization in 

 sugar products: H. H. Peters and F. P. Phbus. 

 The degree of color introduced and decolorization 

 obtained for sugar solutions was determined with 

 a spectrophotometer. The difficulties encountered 

 to create filtrates ' ' optically void ' ' out of impure 

 sugar solutions led to the adoption of an analytical 

 procedure. It is shown that the commonly prac- 

 tised mode of analytical preparation for colori- 

 metrie analyses leads to erroneous conclusions in 

 regard to color introduced and removed; that 

 consistent results can not be attained as the pres- 

 ent criterion for " brilliant filtrates ' ' is far from 

 being synonymous with ' ' filtrates optically void. ' ' 

 Inert material employed in the analytical prepara- 

 tion, such as Kieselguhr, must not be used. It 

 leads to selective action on different wave lengths ; 

 neither is its most brilliant filter-paper-filtrate 

 ' ' optically void. ' ' The final calculation of color 

 in sugar products to a unit basis of "100 Bris, 

 1 cm. ' ' is proposed. The laws governing the ap- 

 plication of the spectrophotometer and tint pho- 

 tometer are discussed and directions are given 

 how to espress color degrees obtained by other 

 colorimeters on this unit basis. Graphs of trans- 

 mission and absorption spectra are presented. 



A discussion of the refraetometer scale for the 

 evaluation of syrups: F. C. Atkinson. A discus- 

 sion of the relative merits of both methods for 

 the grading of glucose and other viscous syrups, 

 being an argument for the adoption of the refrae- 

 tometer reading as the official standard for the 

 commercial valuation of such syrups. This argu- 

 ment is based on the higher degree of accuracy, 

 convenience and saving of time over the method 

 now in vogue. 



Preparation of mannose from ivory nut shav- 

 ings : Paul M. Hoeton. In making mannose from 

 ivory nut shavings, the syrup is usually gummy 

 and difficult to crystallize. If, however, the shav- 

 ings are extracted with sodium hydroxide before 

 being hydrolyzed with sulphuric acid, the final 

 syrup crystallizes from glacial acetic acid without 

 difficulty. If crystallization is slow, it can fre- 

 quently be hastened by freezing the solution under 

 agitation and thawing slowly. Details as to con- 

 centration and temperature are also given. 



Flask calibrating and marlcing device: G. L. 

 Spencer. 



The preparation of a decolorising char from 

 sugar cane bagasse: C. E. Coates. 



A revision of the optical method for analyzing 

 mixtuires of raffin^se and sucrose: C. A. Browne 

 and C. A. Gamble. Recent corrections by Steuer- 

 wald and by Sehrefeld of the Clerget formula for 

 the Herzfeld method of determining sucrose neces- 

 sitate also a revision of the Creydt formulas for 

 analyzing mixtures of raffinose and sucrose. In 

 making this revision, the authors have redetermined 

 the value of the constant for the invert polariza- 

 tion of raffinose and have also determined the 

 values for the influence of temperature upon the 

 polarizations of raffinose before and after inver- 

 sion. Applications are given of the Creydt for- 

 mulas as thus revised to the analysis of mixtures 

 containing known amounts of sucrose and raffinose. 



Preliminary note on tlie causes of caking in 

 '■: M. J. Proppitt. 



Investigation of conditions affecting the quanti- 

 tative determination of reducing sugars by Fehling 

 solution. Elimination of certain errors involved in 

 current methods: F. A. Quisumbing and A. W. 

 Thomas. 



The standardization of rare sugars: H. T. 

 Graber. 



The determination of ash in Cuban raw sugar: 

 Uel S. Jamison and James R. Withrow. Diffi- 

 culty from foamover in ash determination can be 

 eliminated by preliminary heating on electric hot 

 plate before ashing in the usual muffle. A drop or 

 two of vaseline oil also prevents foamover. The 

 sulfate method of ashing used by the Bureau of 

 Standards is found on Cuban raw sugar to give 

 38 per cent, higher results even with the usual 10 

 per cent, modification than its direct incineration. 

 The various other ashing methods in the literature 

 have been compared and a modification of the 

 sulfate method suggested. 



The quantities and properties of lead precipitates 

 from different raw cane sugars: C. A. Browne 

 and H. M. Wilet. A comparison is given of the 

 specific gravities and PbO content of the dried 

 sugar-free lead subacetate precipitates obtained 

 from 3 Cuban centrifugal sugars and 4 Philippine 

 concrete sugars. The lead precipitates from the 

 Cuban sugars had an average sp. gr. of 2.47 and 

 a PbO content of 46.85 per cent., and from the 

 Philippine sugars an average sp. gr. of 2.74 and 

 a PbO content of 49.56 per cent. For a normal 



