34 



INFRA-RED TRANSMISSION SPECTRA. 



Fructose belongs to the anhydrous group of compounds, but is con- 

 sidered here in order to show the great contrast between it and other 

 sugars having water of crystallization. 



J-GLUCOSE (DEXTROSE) (CeH ia O.+H 2 O). 

 (/ = o.i4 and 0.18 mm. Fig. 19.) 



This compound differs from the preceding in having one molecule of 

 water of crystallization. The region of 3 to 4 ju, is very complex and 

 indeterminate, but the water bands appear at 1.5, 4.75 and 6ju, the 



345 

 FIG. 19. Dextrose. 



to 14-) 



latter being quite indistinct. A sample was heated at 110 for four 

 hours which is supposed to render it anhydrous. After standing over 

 P 2 O 5 for several days, several crystals had formed in the glassy mass. 

 These were melted between plates of rock salt. Curve b shows, how- 

 ever, that the water bands still remain, and from the fact that the 

 amorphous material could not be entirely removed from the crystals 

 it is quite probable that there was still some of the hydrous material 

 present. 



