SUMMARY IN the year 1921, J. Marcusson published his sulphonation method for analysing mixtures of Trinidad asphalt and coal tar; and recently it has become necessary to analyse quantitatively mixtures of asphaltic bitumen and coal tar such as are used in road construction. In 1928 the author worked out a sulphonation method for this purpose which gave useful results, and it was adopted as an official German Standard Method, and by the Deutsche Strassenbauverband.
The results that were obtained from the study of this method of analysis enabled conditions to be so chosen that the loss by emulsification in water of the bitumen-sulphonic compound could be balanced by the increase in weight of the asphaltic bitumen during sulphonation. All asphaltic bitumens, however, did not behave in a similar manner; for instance, the bitumen from Trinidad asphalt gave much too low results, whilst Mexican bitumen could be determined with great accuracy. Distillation residues from Galician oil and from Estonian oil schist also did not give normal results.
Carrying, investigation further, the author selected three different asphaltic bitumens of similar softening point, namely, Mexican oil residue, the soluble bitumen in Trinidad asphalt, and a Galician oil residue. The specific gravity and elementary analysis of these three bitumens were determined. It was found that the quantitative analysis by sulphonating a mixture of each with coal tar became the more accurate the lower the specific gravity and the higher the hydrogen content. Asphaltic bitumens with saturated chains and naphthene rings give more correct analytical results than those in which unsaturated chains and aromatic ring compounds predominate. Parallel to this behaviour goes the miscibility with coal tar: asphaltic bitumens of low specific gravity, which give correct values by the author's method, tend to form heterogeneous mixtures and agglomeration of the "free carbon" occurs in mixtures of certain proportions.
In contradiction to this is the complete miscibility of the Trinidad bitumen with coal tar.
The three asphaltic bitumens separated by Suida and Pöll's physical method into oil, oil resins, asphaltic. resins and hard asphalt showed no important difference; but the separated substances, particularly the oils, when mixed with coal tar, showed a quite similar kind of behaviour as when the whole bitumen was mixed with tar, both as regard the sulphonation analysis and the miscibility.
The different fluorescence shown by tar and asphaltic bitumen has not led to any quantitative method of determination; but F. J. Nellensteyn has published a solvent method of analysis based on the use of carbon disulphide, benzine (light petroleum), aniline, and alcohol. This method yields good results but is rather long.
In der Technik der Isolierung von Bauwerken, Tunneln und, Brücken haben