Impure inactive forms result on the polymerization of glycollic aldehyde and also on the oxidation of erythrite, a tetrahydric alcohol found in some lichens.
Bone has shown that when exposed for some time to the sun's rays it undergoes certain polymerization changes which lead to the deposition of a film of heavy hydrocarbons on the surface of the tube.
The formaldehyde at once undergoes a process of condensation oi- polymerization by the protoplasm of the plastid, while the hydrogen peroxide is said to be decomposed into water and free oxygen by another agency in the cell, of the nature of one of the enzymes of which we shall speak later.
More emphasis is, however, now laid on the action of the plastid in polymerization, while the initial stages are still not definitely ezplaincd.
The trimolecular polymerization of numerous acetylene compounds-substances containing two trebly linked carbon atoms, -C: C -, to form derivatives of benzene is of considerable interest.
Fiveand six-membered rings are the most stable and important, the last-named group resulting from the polymerization of many substances; threeand four-membered rings are formed with difficulty, and are easily ruptured; rings containing seven or more members are generally unstable, and are relatively little known.
The globules in the latex are liquid, and the phenomenon of coagulation would seem to consist in the passage of this liquid into solid caoutchouc through the kind of change known as polymerization or condensation, in which a liquid passes into solid without alteration of composition or by condensation with the elimination of the elements of water.
Under certain conditions, as when latex is allowed to stand or is centrifugalized, a cream is obtained consisting of the liquid globules, which may be washed free from proteid without change, but, either by mechanical agitation or by the addition of acid or other chemical agent, the liquid gradually solidifies to a mass of solid caoutchouc. The phenomenon therefore resembles the change known to the chemist as polymerization, by which through molecular aggregation a liquid may pass into a solid without change in its empirical composition.
It has been suggested that urea is formed by polymerization of ammonium carbonate, and formic aldehyde is synthesized from CO 2 and 011 2.
Pfliiger suggests that such compounds arose when the surface of the earth was incandescent, and that in the long process of cooling, compounds of cyanogen and hydrocarbons passed into living protoplasm by such processes of transformation and polymerization as are familiar in the chemical groups in question, and by the acquisition of water and oxygen.
There is very little doubt that the general course of the decompositions follows these iines; but any such simple explanation of the actions taking place is rendered impossible by the fact that, instead of the breaking-down of the hydrocarbons being completed in the coal, and only secondary reactions taking place in the retort, in practice the hydrocarbons to a great extent leave the coal as the vapours of condensible hydrocarbons, and the breaking down of these to such simple gaseous compounds as ethylene is proceeding in the retort at the same time as the breaking up of the ethylene already formed into acetylene and methane, and the polymerization of the former into higher compounds.