_Decomposition of the Phlobaphenes by Fusion with Caustic Alkalies._--It has been mentioned (p. 64) that the reds of different tannins yielded, in addition to protocatechuic acid, either phloroglucol, or acetic acid, or some other member of the fatty acid series. Some tannins, as those of alder and hop, give both phloroglucol and acetic acid, but it is very possible that this arises from the presence of two distinct tannins in these materials. It is stated that all those tannins which yield acetic acid on fusion with potash, also yield considerable quantities of glucose to dilute acids, while the phloroglucide tannins do not do so. Gallic acid fused with caustic soda has been found by Barth and Schroeder to produce a small quantity of phloroglucol, and it is similarly formed by resorcinol and common phenol (Chem. Soc. Jour., xliv. 60). It is therefore possible that in some cases where phloroglucol is detected, it may have been formed by the action of the alkali, and not have been originally a constituent of the tannin. The following is the best method in which to proceed to investigate the products of the action of potash. 20 _grm._ of the red, or of the tannin from which it is derived, or its lead salt, is boiled with 150 _c.c._ of solution of caustic potash of 1·20 sp. gr. for 3 hours, and the liquid is then concentrated with constant stirring till it becomes pasty. It is then cooled and treated with a volume of dilute sulphuric acid slightly more than enough to neutralise the alkali employed. After cooling it is filtered from potassium sulphate and other solid matters, and the filtrate treated with sodium bicarbonate till its wine-red reaction with litmus shows that the sulphuric acid is neutralised. The liquid is then shaken with an equal measure of ether, the ethereous layer drawn off and the treatment repeated several times. On distilling off the ether, phloroglucol is left and may be purified by solution in water, when protocatechuic acid and other products may be precipitated by neutral lead acetate, and filtered off, and the phloroglucol again extracted with ether, and recognised by its reaction with ferric chloride and bromine water, and by its sweet taste.