110 EXPERIMENT STATION EECORD. [Vol.36 



sorbed is detected by the well-known guaiac reaction, and tbe degree of ran- 

 cidity thus determined. The following test is described: 



To about 10 gm. of the sample irti a test tube (solid samples being slightly 

 heated to melt them) from 4 to 5 drops of a 5 per cent aqueous blood or hemo- 

 globin solution, 10 drops of freshly prepared tincture of guaiac, and about 

 10 cc. of water are added and the mixture thoroughly shaken for a few 

 minutes. Rancid fats give a blue color reaction with this test, the strength 

 of which increases with the degree of rancidity, A more decided reaction is 

 obtained if, after shaking the mixture, an equal volume of 96 per cent alcohol 

 is added. 



The guaiac tincture is made by dissolving 5 gm. of gum guaiac in 100 cc. 

 of 70 per cent hot alcohol. The hemoglobin solution is made by dissolving 

 3 gm. of the solid in 100 cc. of water, and, after thorough agitation, letting the 

 solution stand exposed to the air in a wide-mouthed flask. 



The free fatty acids present in the rancid fat on heating to 120° C. do not 

 influence the reaction, while previous heating to 200° hinders the reaction. 



On the localization of acids and sugars in fleshy fruits, E. Demoussy 

 (Compt. Rend. Acad. Sci. [Paris], 161 (1915), No. 15, pp. 4^3-4^5).— Analytical 

 data as to the juices of purple plums, under- and overripe greengages, apricots, 

 under- and overripe peaches, under- and overripe grapes, strawberries, melons, 

 cherries, and tomatoes are submitted. The juices were obtained by subjecting 

 the fruits to increasing pressure. The data include the number of grams of 

 acid (as malic) and reducing and nonreducing sugars per 100 cc. of juice. 



From the data a considerable variation in the acidity of the various fruits 

 was observed. The variations in the sugar content were, however, relatively 

 less. 



It is deemed probable that the cells which offer the least mechanical resist- 

 ance and are the most permeable do not have the same composition as those 

 which furnish the sugars. The difference in their physical structure, probably 

 a variation in the tliickness of their walls, is accompanied by a difference in 

 the chemical composition of their contents. There is localization, but it is 

 not the same for all the fruits. Sometimes the most resistant cells contain the 

 least amount of acid and reducing sugars and are rich in saccharose. Some- 

 times the reverse is true. The composition of the fruit thus varies in different 

 parts in spite of its apparent homogeneity and uniform distribution of water. 

 The semipermeability of the protoplasm prevents the diffusion of soluble 

 material. 



This localization of soluble material explains the peculiar fact observed in 

 certain fruits, especially plums and apricots, of an increased acidity in the 

 cooked fruit. By crushing the fruit cold, as acid a juice is obtained as by 

 cooking. It is thought that this increased acidity can not be attributed to any 

 diastatic action, fermentation, or oxidation, but to a dissociation of those cells 

 in which the acid is localized. 



Studies in the chemistry and physiology of the leaves of the betel vine 

 (Piper betle) and of the commercial bleaching of betel-vine leaves, II, H. H. 

 Mann and V. G. Patwardhan {Mem. Dcpt. Afir. India, Chcm. Scr., Jf (1916), 

 No. 7, pp. 281-822). — Continuing the work previously noted (E. S. R., 31, p. 

 108), the authors report and discuss analytical data on the moisture, reducing 

 and nonreducing sugars, starch, tannin, ether extract and essential oil, nitrate, 

 and acid content of leaves picked in the morning, at noon, and at night; the 

 varieties of betel-vine leaves, their qualities, and the essential oil in them ; and 

 the cliemistry of the essential oil of the leaves. The commercial bleaching of 

 the betel-vine leaf is also discussed in some detail. 



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