756 SUGARS. 



6 parts of boiling water, and insoluble in alcohol. It is a bibasic 

 acid, of which the salts of an alkaline base are soluble in water, 

 and those which contain an alkaline earth, or the oxide of a 

 metal proper, are insoluble. Mucic e//i<?r,2C 4 H 5 O + C 12 H 8 O 14 , 

 is solid and crystallizes in quadrilateral colourless prisms. Modi- 

 fied mucic acid is produced by boiling a concentrated' solution of 

 mucic acid, or evaporating it by heat. Its acid powers are 

 more distinct than those of mucic acid, and it is also distin- 

 guishable from the latter by the physical properties of its salts. 

 The modified acid is either isomeric with "mucic acid, or con- 

 tains the elements of an atom of water in addition (Malaguti). 

 Pyromucic acid, C 10 H 3 O 5 + HO, is produced in the dry distilla- 

 tion of mucic acid, by the separation of 6 atoms of water, and 

 2 atoms of carbonic acid ; 



C 12 H 8 O 14 + 2HO==C 10 H 3 O 5 and 6HO and 2CO 2 . 



It forms elongated, white and brilliant plates, which fuse at 

 266 (130 cent.), and volatilise without residue at a tempe- 

 rature a little higher. It is soluble in 26 parts of cold and in 4 

 parts of boiling water, dissolves easily in alcohol, and is not 

 altered by nitric acid. It forms a class of monobasic salts, 

 including pyromucic ether C 4 H 5 O-f C 10 H 3 O 5 , which is solid. 

 Pyromucic ether absorbs 4 atoms of chlorine gas and becomes 

 liquid, without the liberation of any hydrochloric acid, forming 

 a compound, which Malaguti names chloropyromucic ether, 

 C 14 H 8 C1 4 O 6 , but of which the true constitution is uncertain. 



MUSHROOM SUGAR. 



This sugar, of which the formula is C 12 H 13 O 13 , according to 

 an analysis by MM. Liebig and Pelouze, was obtained by M. 

 Wiggers by treating the tincture of the ergot of rye by water. 

 It crystallizes, and is soluble in water and alcohol, but not in 

 ether. Mushroom sugar is also fermentable by yeast, and 

 diffuses the odour of caramel when carbonised by a high tem- 

 perature. This sugar does not throw down sub-oxide of copper 

 from a boiling solution of the acetate, the only property by 

 which this sugar is distinguished from the ordinary species. 



