BUEEAU OF CHEMISTRY. 219 



SUGARS AND SIRUPS. 



Bulletfh 466, "Maple Sugar: Composition, Methods of Analysis, 

 and Effect of Environment," has been issued. Methods for the prep- 

 aration of xylose, rhamnose, arabinose, and maltose have been per- 

 fected. The preparation of dulcite from galactose has been carried 

 out upon a large laboratory scale. The optical-crystallographic 

 properties of the pentose sugars and of the rare trisaccharid melezi- 

 tose have been determined. Melezitose has been found to occur in 

 large proportion in a manna from the Douglas fir, and has also been 

 found in the free crystalline form in honey of the honey-dew type 

 from Pennsylvania and Maryland. A number of articles have been 

 published upon these subjects, as well as upon the acetates of certain 

 sugars and upon the amides of certain oxy-acids. 



Much progress has been made in learning the conditions for pre- 

 paring carbon of high absorptive power for use in clarifying sirups. 

 The methods for the clarification and filtration of sugar-cane sirup 

 have been improved. 



BEVERAGES AND VINEGAR. 



Two papers have been published upon the carbonation of beverages 

 and one upon the occurrence of manganese in water supplies. De- 

 partment Bulletin 656. " Concord Grape Juice : Manufacture and 

 Chemical Composition," has been issued, and a similar study upon 

 white grape juice is in progress. Extensive, authentic data on Amer- 

 ican wines, accumulated through more than a decade, have been com- 

 piled and filed for reference, under the title " Wine Investigation : 

 Composition and Natural Acid Reduction of Wines Made from Na- 

 tive American Grapes," thus closing this project. The investigation 

 of the sectional, seasonal, and other variations in the composition of 

 fermented apple juice (cider-vinegar stock), begun in 1916, has been 

 extended. Some of the results have been tabulated for the benefit 

 of food and internal-revenue officials. A study of the changes that 

 cider undergoes during fermentation and prolonged storage and its 

 subsequent conversion into vinegar in rotating generators has been 

 published. As a conservation measure, studies were made upon the 

 use of sugar substitutes in soft drinks. A series of papers on the 

 subject has been published in the trade press, and the formulae recom- 

 mended are in actual use. 



FRUITS AND VEGETABLES. 



A study upon the composition of loganberiy juice has been com- 

 pleted. The results of an investigation of the acid content of fruits 

 and of a study of arsenic in sulphured food products due to the use 

 of sulphur containing arsenic have been published. Department 

 Bulletin 581, " Microscopical Studies on Tomato Products," corre- 

 lating the amount of decayed material used in the preparation of 

 tomato products with the appearance of these products under the mi- 

 croscope, has been issued. The general use of apple pomace and the 

 preparation of pectin from apples and other sources has been studied. 

 The use of pectin as a filler in the preparation of jellies and similar 

 products and for the preparation of jellies from fruits which contain 

 but a small amount of pectin is growing, and brings with it a number 

 of problems demanding solution. 



