I have already referred to the fact that solutions of hop-bitter acid, if left standing too long, assume a yellow color, and on evaporation leave only a yellow resinous residue. This, as its reaction shows, evinces a complete analogy with the crystallized acid. The dark-colored mother solution, from which the crystalline cakes of bitter acid are obtained, contains a large proportion of this resinous compound, which can be isolated by treatment with a weak soda-lye; this substance, like the crystallized acid, is soluble in alkalies, and can be precipitated from an alkaline solution by an acid. Old hops furnish far less crystallizable acid than new hops; from some samples I have been able to obtain only a few crystals; the remainder had been transformed into the resinous modification.
If pure hop-bitter acid be pulverized and exposed to the atmosphere, it soon turns yellow and the surface assumes a resinous consistency. At the same time, a more pronounced odor of fatty acids and aldehydes is apparent. Still more rapidly will this oxidation occur if a thin layer of an alcoholic solution of the acid is allowed to evaporate in the air. On the other hand, we can allow hop-oil to stand for days without its odor being perceptibly changed; it appears to me more than probable that the peculiar smell of old hops is due far more to the oxidation of the bitter substance than to the oxidation of oil.
Hop-bitter acid appears to possess the character of an aldehyde and of a weak acid; for the present I am not in a position to state its constitution more clearly. Most of the oxidizing processes have an energetic effect on it, forming also considerable quantities of valerianic acid.
The question as to whether the hop owes chiefly to this acid and its resinous modifications the property of imparting a pronounced bitter flavor to a solution, I must for the present leave unanswered. The acid and its isomer are both insoluble in water; they are, on the other hand, very readily dissolved in hop oil; they also furnish a tolerably bitter solution, if boiled for a long time in water, probably on their account of their gradual decomposition. I will not for the present go further into the subject, as I hope soon to be in a position to give more definite information.
ST. PAUL'S VICARAGE, FOREST HILL, KENT.
This vicarage, for the Rev. Frank Jones, has recently been completed from the designs of Mr. E.W. Mountford, A.R.I.B.A.; of 22 Buckingham Street, Strand, W. C., and Mr. H. D. Appleton, A.R.I.B.A., of the Wool Exchange, Coleman Street, E. C., who were the joint architects. The builder was Mr. William Robinson, of Lower Tooting, S. W. The walls are of yellow stock bricks, with red brick arches, quoins, etc., the gables being hung with Kentish tiles and the roofs covered with Broseley tiles. The internal joinery is of pitch pine.
ST. PAUL'S VICARAGE, FOREST HILL.--VIEW FROM ROAD.