December 22, 1922] 



SCIENCE 



729 



from various sources. There are also given some 

 tentative conclusions as to some of the under- 

 lying principles in the preparation of decolor- 

 izdng chars. 



The influence of borax on the polarising power 

 of mannitol: C. A. Browne. 



The contraction in volume of sucrose solutions 

 upon inversion: E. F., Jackson. 



The Valleg rotary filter press: W. D. Horne. 

 This newly introduced filter press differs from 

 the preceding tj^pes of leaf presses in having its 

 filtering discs set upon a hollow horizontal shaft 

 which revolves slowty during filtration, insuring 

 uniformity of deposit of cake upon the leaves. 

 Paper pulp is used as the filtering medium, which 

 gives greatly increased speed of filtration, while 

 the uniformity of the cake allows of sweetening 

 off with the minimum amount of water and gives 

 a very low sucrose content in the washed cake. 

 The washing out is particularly effective, and the 

 arrangement of parts allrnvs of very rapid dis- 

 charging, cleaoising and refilling. 



Comparative color determinations in cane sirups 

 and molasses: F. W. Zeeban and S. Btall. The 

 object of this investigation was to ascertain 

 whether it was possible Avith the Hess-Ives tint 

 photometer to detect any difference in the spe- 

 cific transmissive index of cane products when 

 the sample was in one instance dissolved in water 

 and filtered "\vith a small amount of kieselguhr, as 

 previously practiced by the authors, and in the 

 other diluted with white sugar sirup and filtered 

 according to Peters' and Phelps' method. It 

 was found, with twelve cane products represent- 

 ing the entire color range, that water dilution 

 gave too low figures in 70 per cent, of the deter- 

 minations, and too high figures in the remainder; 

 the average difference was surprisingly small, 

 — 0.78 per cent, of the color for the red glass, 

 — 2.13 per cent, for the green glass and — 6.28 

 per cent, for the blue glass. Only in a few indi- 

 vidual determinations did the error due to water 

 dilution exceed to any extent that attributable 

 to the permissible error in the readings them- 

 selves. With the Hess-Ives instrument, therefore, 

 the method previously used by the authors is 

 sufficiently exact for practical factory purposes. 

 Conditions are, of course, different when the 

 spectrophotometer is used. 



The countercurrent application of Tcelpahar in 

 the decolorisation of sugar and syrup : J. W. Tttr- 

 RENTINE. A process is described for the continu- 

 ous, automatic and countercurrent application of 

 kelpohar in the decolorization of sugar and other 

 solutions and liquids. Use is made of the best 



filter practice, the process admitting of the em- 

 ployment of the most adaptable of modern filters. 

 Thus vacuum or pressure filters or centrifugals 

 may be employed, depending on the nature of 

 the liquid to be filtered. The kelpchar by this 

 process is admitted at one end of the apparatus, 

 is applied countercurrent-wise to the liquid under- 

 going decolorization in as many applications as 

 desired, and is discharged as spent cake ; while 

 the crude liquid is admitted at the end of the 

 apparatus at which the spent cake is discharged 

 and is delivered in a completely purified state at 

 the other, upon entering tlie apparatus coming 

 into contact with the practically spent carbon and 

 finally before emerging undergoing treatment 

 with the fresh kelpchar entering. In the one- 

 stage application of a decolorizing carbon, the 

 carbon first loads itself up with those impurities 

 most easily removed, and finally adsorbs those 

 least easily taken up. Thus an excess of the 

 reagent is required, and at that an excess prob- 

 ably out of proportion to the decolorization to be 

 effected. In the present system kelpchar that has 

 been used to adsorb the impurities most difficult 

 to remove is still available with unimpaired 

 power to adsorb the impurities more easily ad- 

 sorbed. In this way full use is made of the 

 decolorizing properties of the kelpchar and the 

 most efficient application of that material results. 

 The advantages gained are that smaller quanti- 

 ties of kelpchar are in use and require reactiva- 

 ting and losses of values are correspondingly re- 

 duced. The process admits of continuous and 

 automatic operation, and labor and laboratory 

 supervision are reduced to a minimum. 



Estimation of caramel in sugar products: A 

 criticism of the Ehrlioh method: G. P. Meade. 

 Ehrlich bases his method on the claim that sac- 

 charan, a component of caramel, is not precipi- 

 tated by lead subacetate. The present investiga- 

 tion shows that this is true only with saecharan 

 dissolved in distilled water ; if any of the ordinary 

 impurities are present that form a precipitate 

 with lead the saecharan is carried down with the 

 precipitate. Known amounts of saecharan and 

 of caramel, added to molasses solutions, are 

 largely removed by clarification with lead sub- 

 iaeetate. Therefore, the Ehrlich method is value- 

 less. 



A steam-heated laboratory vacuum pan: J. F. 

 Brewster. The body of the vacuum pan con- 

 sists of an inverted bell jar with open wide neck 

 fitted with a rubber stopper through which pass 

 the leads of the %6 or y^ inch coil of copper 

 tubing, the feed and drain-off pipes. A second 



