MALTOSE. 225 



changed by the presence of other inactive substances. The specific 

 rotation is (a) D = +66.5. 



Saccharose acts indifferently toward MOORE'S test and to the ordinary 

 reduction tests. On continuous boiling it may reduce an alkaline copper 

 solution, perhaps on account of a partial inversion. It does not ferment 

 directly, but only after inversion, which can be brought about by an 

 enzyme (invertin) contained in the yeast. An inversion of cane-sugar also 

 takes place in the intestinal canal. Cane-sugar does not combine with 

 hydrazines. Concentrated sulphuric acid blackens cane-sugar very 

 quickly even at the ordinary temperature, and anhydrous oxalic acid 

 does the same on warming on the water-bath. Various products are 

 obtained on the oxidation of cane-sugar, dependent upon the variety of 

 oxidizing agent and also upon the intensity of the action. Saccharic acid 

 and oxalic acid are the most important products. 



The reader is referred to complete text-books on chemistry for the 

 preparation and quantitative estimation of cane-sugar. 



Maltose (MALT-SUGAR) is formed in the hydrolytic cleavage of starch 

 by malt diastase, saliva, or pancreatic juice. It is obtained from gly co- 

 gen under the same conditions (see Chapter VII). Maltose is also pro- 

 duced transitorily in the action of sulphuric acid on starch. Maltose 

 forms the fermentable sugar of the potato or grain mash, and also of the 

 beerwort. 



Maltose crystallizes with one molecule water of crystallization in fine 

 white needles. It is readily soluble in water, rather easily in alcohol, 

 but insoluble in ether. Its solutions are dextrorotatory; and the specific 

 rotation is variable, depending upon the concentration and temperature, 

 but is considerably stronger than glucose, 1 and is generally given as 

 (a) D =+137 to 138. Maltose ferments readily and completely with 

 yeast, and acts like glucose in regard to the reduction tests. It yields 

 phenylmaltosazone on warming with phenylhydrazine for 1J hours. 

 This phenylmaltosazone melts at 205 C., and is more soluble in hot 

 water than the glucosazone. Maltose differs from glucose chiefly in the 

 following: It does not dissolve as readily in alcohol, has a stronger dex- 

 trorotatory power, and has a feebler reducing action on FEHLING'S solu- 

 tion; 10 cc. FEHLING'S solution are, according to SoxHLET, 2 reduced 

 by 77.8 milligrams anhydrous maltose in approximately 1 per cent solution. 



Isomaltose. This variety of sugar, as has been shown by FiscHER, 3 

 is produced, as are dextrin-like products, by reversion, and by the action 

 of fuming hydrochloric acid on glucose. A re-formation of isomaltose 



1 See Hoppe-Seyler-Thierfelder's Handbuch, 8. Aufl. 



2 Cited from Tollens' Handbuch. der Kohlehydrate, 2. Aufl. 1, 154. 



3 Ber. d. deutsch. chem. Gesellsch., 23 and 28. 



