Gelatine---------------Precipitate. Ferric chloride--------Deep blue coloration. Aqueous ammonia--------Cherry-red coloration. Lead acetate-----------White precipitate, insoluble in HNO_3. Aniline hydrochloride--Precipitate. Bromine water----------No reaction. The product brought to acidity 10, yielded on analysis the following figures:-- Tanning matters------------------ 25.2 per cent. Soluble non-tannins-------------- 56.3 " Insolubles----------------------- 0.0 " Water---------------------------- 18.3 " ------------- 100.0 per cent. Tanning experiments with this substance yielded white and soft leathers, which were indistinguishable from those tanned with Neradol D. A characteristic feature of this synthetic tannin is its behaviour in concentrated form towards pelt, which is not attacked by it, but is readily tanned even at such high concentrations. An explanation of this is to be found in the large quantity of salts present in the product. A disadvantage of this synthetic tannin is its complete incapability of dissolving phlobaphenes, which is even so far extended as to precipitate otherwise easily soluble tannins when adding it to solutions of the latter in comparatively large proportions; here, again, the salts are responsible for this behaviour, their large quantities effecting a salting out of the natural tannins. The class of aldehyde condensations also comprises that of inducing condensation by means of sugars; if phenolsulphonic acid is heated with glucose, a reddish-brown liquid results, which is soluble in water. The solution exhibits reactions similar to those of Neradol D. It is, however, not possible, by this method of condensation, to prepare as highly concentrated products as is possible in the case of Neradol D, since employing sugars as condensation agents means liberation of a large volume of water. Analysis of this product, using the shake method, gives a tannin content of 16.2 per cent; tanning experiments demonstrated that the time of tannage, using a 2° Bé. solution, was the same as that required by Neradol D, and yielded a leather, the surface of which was reddish-grey, the inner layers being white, but which is otherwise very similar to Neradol D tanned leather. [Footnote: Austr. Pat, 69,375, 69,376, 69,377.] 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:--