8o rUNDAMENTALS OF SUBMICROSCOPIC MORPHOLOGY I 



difficulty that gels whose framework units consist of only a few 

 parallel chain molecules do not answer to Nageli's original definition, 

 because a small number of chain molecules are not capable of forming 

 a crystal lattice. With still finer strands of the gel structure, it is true, 

 it ultimately consists only of chain molecules and the micellar frame- 

 work has changed into a molecular frameivork^ as has been pointed out 

 on page 73. Just as in the transition from colloid to molecular disper- 

 sions, there also exist transitional forms between (a) gels with micellar 

 strands and (b) gels with chain molecules as structural units. In gels 

 with a molecular framework the particle size of the two components 

 of the system are not similar as in the case of solvent and solute 

 molecules in a true solution. In principle they remain different in a 

 morphological sense as framework and interstitial substance. 



In the case of micellar systems possessing strands with a thickness 

 of several molecules, a distinction should be made between processes 

 which occur in the meshes of the network (/>^/^r/;//V«'//<«r) and those occur- 

 ring inside the beams of the frame, i.e., in the crystal lattice {intra- 

 micellar). In the same sense the expression "intramicellar" is used for 

 cation exchange inside layer lattices (Wiegner, 1935 ; Bottini, 1937). 

 With the aid of the concepts "micellar", "intermicellar" and "intra- 

 micellar", all processes occurring in gel structures can be described 

 unambiguously. By a relatively sUght change in concepts we thus 

 preserve a nomenclature which has done good service for 90 years, 

 and renders honour toNAGELi,who laid the foundations of the research 

 on biological gels. 



In Table X we have recapitulated the most important points which, 

 according to our definition, distinguish the reticular gel from its 

 counterpart, the corpuscular sol. As in the case of dispersoids (Table 

 II, p. 16), the components of a gel can occur as gases, hquids or 

 solids, with the restriction, however, that the micellar component must 

 always be solid (Table XI). If the intermicellar substance is a gas or a 

 liquid, we have to deal with network structures or capillary structures. 

 If it is a solid, however, solidified gels result, showing clearly in 

 contrast to dispersoids that the two components are completely 

 equivalent as regards the arrangement in space. 



The micellar structure is determined by the micellar strands, by the 

 type of bonds between them and by the intermicellar substance. For 

 a given type of micellar units, however, the gels can be built up with 



