PHYSIOLOGICAL CHEMISTRY. 

 RELATIONS OF THE CARBOHYDRATES. Continued. 



CARBOHYDRATES PROPER. 



Following the usual classification we have then : 



Monoses or monosaccharides,. 

 Saccharodioses or disaccharides, 

 Saccharotrioses or trisaccharides, 

 'Polysaccharides. 



These bodies are mostly of vegetable origin, but some, such 

 as sugar of milk, are found in the animal kingdom. The syn- 

 thetic preparation of some of these sugars has been accom- 

 plished, starting from either formaldehyde or the mixture 

 called above glycerose. When formaldehyde, CH 2 O, is treated 

 with lime or other weak bases it polymerizes or condenses 

 to a mixture of sugars, one of which has been isolated in 

 pure condition and is known as a-acrose. By the condensa- 

 tion of the mixture of glyceraldehyde and dioxy-acetone (gly- 

 cerose or triose) mentioned in the table above the same acrose 

 has been obtained, This acrose is identical with the sugar 

 mixture known as (d + /) -fructose. 



A number of sugars have also been obtained by a general 

 method of synthesis which depends on the fact that as alde- 

 hydes and ketones they have the power to unite with hydro- 

 cyanic acid and produce nitriles of acids which may be reduced 

 to new aldehydes with a larger number of carbon atoms than 

 the original substance contained. This may be illustrated by 

 starting with arabinose, C 5 H 10 O 5 , as figured above. This 

 with hydrocyanic acid yields a cyanide as follows : 



