85 



green fluorescence wliicli disappears through acids ; it separates on 

 access of diluted acids into sugar and FraxetinzzCso H12 Oig, a 

 crystalline body slightly acerb to the taste. 



Fraxiuin obtained, according to Kellei', from the bark of the 

 Ash-tree, is mannit. 



Fruit Sug'ar (LiEV0-GLUC0SE) = Ci2 H12 O12. Cane-sugar in 

 solution by keeping, or more quickly by heating with diluted acids, 

 is converted into inverted sugar, and instead of rotating to the 

 right, acquires the property of rotating to the left; which change 

 amounts for every 100° of the original dextro-rotation, to 06° 

 IfBvo-rotation at 14°, provided the inversion has been complete. 

 During inversion cane-sugar assimilates 5-26°/^ water, forming 

 inverted sugar, i.e., a mixture of equal parts of dextro-glucose (grape- 

 sugar) and of laevo-glucose : 2 C12 Hn On + 2 H0=rCi2 H12 O12. 



Fruit-sugar occvirs as inverted sugar in honey, in many succu- 

 lent fruits, and other saccharine vegetable parts. Its isolated 

 occurrence has as yet not been proved with certainty, yet some 

 kinds of pears and apples contain more fruit than grape-sugar. 

 To obtain Fruit-sugar pure, mix ten parts inverted sugar intimately 

 with six parts lime-hydrate and 100 parts water, whereby the at 

 tiirst fluid mass congeals after some shaking, and on hard pressui'e 

 allows gi-ape-sugar lime to run off, while the solid residue, de- 

 composed after washing by oxalic acid, yields Fruit-sugar. In like 

 manner the inverted sugar, occurring in fruits, may be decomposed. 

 Pure Fruit-sugar is, after heating to 100°, a colourless, uncrys- 

 tallisable syi'up, or an amorphous, hai-d mass, as sweet as cane- 

 sugar, dissolves more readily in alcohol than grape-sugar, under- 

 goes directly with yeast the vinous fermentation, and behaves 

 towards alkaline solutions of tartarate of coj^per like grape-sugar. 



Fruittaunic Acid. Occurs in unripe apples, pears, and some 

 other fruits, and disap})ears on ripening, while the amount of sugar 

 increases proportionately. By mixing the filtered juice of the 

 above fruits with starch paste and adding iodine, iodine-starch is 

 formed, but not before the whole of the tannic acid has been con- 

 verted into an iodine compound. To obtain the latter, add to the 

 juice of unripe fruits tincture of iodine in small quantities until 

 the colour of the iodine no longer disappears ; a brown precipitate 

 is formed after a few moments, which has to be washed with 

 water. Yellow, amorphous powder, insoluble in water and alcohol, 

 is decomposed by boiling with diluted acids, yielding grape-sugar. 



Fuiliai'ic Acid = Cs II2 Oe + 2 HO, also called boletic, lichenic, 

 and paramaleic acid, the latter on account of its occurrence, 

 together with maleic (equisetic) acid, among the products of the 

 destructive distillation of malic acid; has been found hitherto in 

 Fumariaceae, Lichenes (for instance, Cetraria Islandica), Fungi 



