Relatively to its capability of solubilising phlobaphenes, this product exhibits similar properties to that obtained by merely heating phenolsulphonic acid, to a slight extent only solubilising quebracho extract, which, on diluting the mixture, is completely thrown out of solution.
5. Condensation with Glycerol
Phenolsulphonic acid, when heated with glycerol, undergoes the process of condensation, and forms a brown fluid, which, when brought to acidity 10, exhibits the following reactions:—
Gelatine————————-Precipitate.
Ferric chloride—————Brown-black coloration.
Lead acetate——————-White precipitate, insoluble in
HNO_3.
Aniline hydrochloride——Slight precipitate.
Tanning experiments with this partly neutralised product resulted in a very gradual conversion of the pelt into a greenish-grey coloured leather; the colour, however, does not penetrate the pelt and is hence caused by colloidally suspended impurities. If the solution is filtered through a filter candle, a somewhat clearer solution results, but the latter also tans very slowly and yields a brown coloured leather.
Analysis of the partly neutralised product reveals a tannin content of 17.6 per cent. A 2° Bé. solution of the non-neutralised product showed a rapid tanning effect at first, when brought into contact with pelt, on which it had a strong swelling effect, and to which it imparted a greenish colour; the tanning effect, however, slowed down considerably, after a few days, and the solution penetrated the pelt only very gradually; this is probably due to the presence of large quantities of colloidally suspended impurities, which, when the substance is partly neutralised with the formation of salts of the sulphonic acids, are brought into true solution and hence penetrate the pelt with greater rapidity.
INDEX OF AUTHORS
Adler
Appelius
Ashmore
Bader
Badische Anilin u.(German abbreviation for "und") Soda-Fabrik
Baekeland
Baeyer
Berzelius
Biginelli
Boehringer & Sons
Bottinger
Braconnot
Buff
Caro
Chem. Fabrik Jucker & Co.
Chevreul