122 



H. E. SCHROEDER AND S. K. BOYD 



SURFACE-AREA AND AFFINITY 



oOo 



NIL 



MODERATE 



HIGH 



Fig. 9 



of benzidine derivatives, where correlations have been made between high af- 

 finity and a spacing between azo groups which correspond to the 10.3 A period 

 between appropriate hydroxy! groups in a cellobiose crystal unit. Specific ar- 

 rangements such as this may certainly promote affinity, but as has been shown 

 by Robinson, cellulose has so many available hydroxyl groups that explanation 

 of affinity exclusively through such coincidence is not tenable. It is certainly 

 true, however, that dyes for cellulose are unusually sensitive to minor changes 



SOLUBILITY AND AFFINITY 



NoOsS 

 Na03S' 



O3S 9^' HO 



HIGH AFFINITY 



DIAMINE BLUE 6 6 



NaOsS 

 Na03S 



-, 1^ __ HO. SOsNo 



^ — *^^ r\ \4 NO AFFINITY 



BOsNa 



NAPHTHOL BLACK B 



Fig. 10 



