Mannite, Or Mannitose, also called sugar of manna and sugar of mushrooms (C6H14O6), one of the glucoses, which was discovered by Proust, and its composition determined by Lie-big. It exists in a great number of vegetables, and in the saccharine juices which have undergone viscous or lactic fermentation; it is generally extracted from manna, by digesting this substance with boiling alcohol, filtering while hot, and crystallizing; it should be purified by repeated crystallizations. On the transformation of starch into glucose by boiling with dilute sulphuric acid, it is also formed as a secondary product; and finally Linnemann in 1862 obtained it by the action of nascent hydrogen on glucose. Mannite is a solid substance, fusible between 160° and 165° C, and when once melted it can remain liquid at 140° ('. It exercises no action on polarized light; it dissolves in 6 1/2 times its weight of water at 18oC., and in 80 parts of cold alcohol of the strength of 89 percent., and much more readily in boiling alcohol. It is not soluble in ether, and absolute alcohol only dissolves 14 percent, of its weight of mannite. Mannite crystallizes in anhydrous, thin, colorless, four-sided, silky prisms, which sometimes grow to a considerable size.

It does not ferment except under very unusual conditions; does not reduce oxide of copper to the state of suboxide, but hinders the precipitation of sulphate of copper by the lived alkalies, causing the formation of a beautiful blue-purple solution instead, in its chemical character, mannite is now regarded as a polyatomic (hexatomic) alcohol. Bert helot has shown its close analogy to glycerine, and has obtained a great variety of salts (called man-mtanides) from it by heating mannite with different acids to a temperature of between 200° and 250 ('. With a mixture of nitric and sulphuric acids it gives nitro-mannite The nitrates of silver and mercury and the chlorides "I silver and mercury are not reduced by mannite even at boiling heal; the acetate and oxide of silver, however, if heated with mannite or left in contact with it at ordinary temperatures, yields a speculum of silver. Compounds of mannite with barium, calcium, strontium, etc, have been prepared by Ubaldini. In the presence of beer yeast mannite does not ferment; but if its solution be maintained at 40° C, after having been mixed with chalk and poor cheese, pancreatic tissue, or albumen, fermentation takes place, hydrogen and carbonic anhydride are disengaged, and alcohol is produced along with lactic and butyric acids.