74 1IOW CHOPS GRO\V. 



Afannite, C 6 H, 4 O B , is abundant in the so-called manna of the apoth- 

 ecary which exudes from the bark of several species nt' ash that 

 grow in the eastern hemisphere (t'raxintis onm* and rotti/niijniiii). It 

 likewise exists in the sap of our fruit trees, in edible mushrooms, and 

 sometimes is formed in the fermentation of sugar (viscous fermenta- 

 tioii). It appears in minute colorless crystals ami lias a sweetish taste. 

 It may be obtained from dextrose and levulose by the action of 

 nascent hydrogen as liberated from sodium amalgam and water, 

 CeH^O, + H 2 = C,H 14 6 . 



Dulcite, C B H U O , is a crystalline substance found in the common cow- 

 wheat (Melampyrinn nemorosum) and in Madagascar manna, li N 

 obtained from milk-sugar by the action of sodium amalgam. 



The isomeres mannite and dulcite, when acted on by nitric acid, .-in- 

 con verted into acids which are also isomeric. Mannite yields sacchar> 

 acid, which is also formed by treating cane-sugar, dextrose, levulose, 

 dextrin and starch with nitric acid. Dulcite yields, by the same treat- 

 ment, mucic acid, which is likewise obtained from arabin and other 

 gums. Milk-sugar yields both saccharic and mucic acid. Saccharic 

 acid is very soluble in water. Mucic acid is quite insoluble. Both 

 have the formula C 6 H, O 8 . 



The Pectin-bodies. The juice of many ripe fruits, when mixed with 

 alcohol, yields a jelly-like precipitate which has long been known 

 under the name of pectin. When the firm flesh of acid winter-fruits is 

 subjected to heat, as in baking or stewing, it sooner or later softens, 

 becomes soluble in water and yields a gummy liquid from which by 

 adding alcohol the same or a similar gelatinous substance is separated. 

 Fremy supposes that in the pulp " pectose " exists which is transformed 

 by acids and heat into pectin. 



EXP. 33. Express, and, if turbid, filter through muslin the juice of a 

 ripe apple, pear, or peach. Add to the clear liquid its own bulk of 

 alcohol. Pectin is precipitated as a stringy, gelatinous mass, which. 

 on drying, shrinks greatly in bulk, and forms, if pure, a white sub- 

 stance that may be easily reduced to powder, and is readily soluble in 

 cold water. 



Pectosic and Pectic Acids. These bodies, according to Fremy. com- 

 pose the well-known fruit-jellies. They are both insoluble or nearly 

 so in cold water, and remain suspended in it as a gelatinous mass. 

 Pectosic acid is soluble in hot water, and is supposed to exist in those 

 fruit-jellies which liquefy on heating but gelatinize on cooling. Pec- 

 tic acid is stated to be insoluble in hot water. According to Fremy. 

 pectin is changed into pectosic and pectic acids and finally into mrta- 

 pectic acid by the action of heat and during the ripening process. 



EXP. 35. Stew a handful of sound cranberries, covered with water, 

 just long enough o make them soft. Observe the speedy solution of 

 the firm pulp or "pectose." Strain through muslin. The juice contains 

 soluble pectin, which may be precipitated from a small portion by 

 alcohol. Keep the remaining juice heated to near the boiling point in 

 a water bath (i. e., by immersing the vessel containing it in a larger 

 one of boiling water). After a time, which is variable according to 

 the condition of the fruit, and must be ascertained by trial, the juice 

 on cooling or standing solidifies to a jelly, that dissolves on warming. 

 and reappears again on cooling Fremy's pectosic acid. By further 



