Abstract

In checking up as to which substances are present in latex, we find the following: protein, which can act as a protective colloid, lipoids (sterols, lecithin which can protect the sterol, esters of sterols), and further the contents of the globules, which is probably viscous. In view of the above considerations it is my opinion that one can picture latex as follows: The rubber globules are suspended in a protein emulsion, and have a lipoid wall and a viscous content. In the case of ordinary coagulation, where the p_H becomes 4.8, one might therefore form the idea that only the protein flocculated and formed a gel in which the globules stay put. Investigations by Rona and Deutsch have shown that the iso-electric point of lecithin is very much influenced by the presence of protein, and it is therefore probable that the lipoid substances will be flocculated already at that lower p_H. When both protein and lecithin, the two hydrophilic colloids, are flocculated, there still remains the hydrophobic colloid sterol, which can easily be flocculated by the salts present. Then the contents of the globules are no longer protected, but stay included between the gels. The latter flocculation is irreversible and, therefore, once coagulation has taken place, inversion is impossible.