found as a minimum 8 per cent., and as a maximum 18 per cent. of hop dust. It is a well-known fact that the hops of different countries are not equally good; the difference in the quantity of the yellow powder may, among others, be one of the causes; but, as in the manipulations which the hops undergo, the yellow powder may be easily detached, it would be wrong to conclude from the experiments of Payen and Chevallier, that, in the hops as they are in the field, there exists such a difference in the quantity of powder; during the carriage a small quantity may in some way or other be lost.

Wimmer found in 100 parts of hops 20 parts of powder to 80 parts of scales. But as it was impossible to separate from the flowers all the particles of yellow dust held, he was of opinion that about half more ought to be added. He found, by analysis, the following percentages:

Lupuline. This name has been given by Ives to the yellow dust which covers the folioles of the female flower of hops. Later on Ives, Payen, Chevallier, and Pelletan gave the same name to the bitter substance contained in the dust.

Besides the oil which is obtained by distillation, and the tannic acid, which is also not without value as regards the preparation of beer, the resin and the bitter substance especially deserve to be distinguished. They are both obtained by treating with alcohol the yellow dust of the hops. Water is added to this tincture, and it is distilled, which causes the separation of a large quantity of resin. The tannic acid and malic acid are saturated by means of lime, and the liquor is evaporated. If the residue is treated by ether to further obtain a small remaining quantity of resin, then by alcohol, the bitter substance dissolves in the alcohol, and may be separated from it by evaporation.

Lupuline, seen under the miscroscope, resembles an acorn in its cupule; it is a gland composed of a hidden cupule, surrounded by a membraneous sac, called the cuticule, which contains the products of the secretion, constituting the essential oil of hops.

This essential oil is a clear green liquid, slightly bitter, very aromatic, of the mellow odour of fresh hops; its specific weight 908 at +16° C.; it is but slightly soluble in water, very soluble in alcohol, and boils at + 240° C. Iodine and bromine turn it brown and alcoholized sulphuric acid reddens it. The essential oil is composed of an eleoptine and a stearoptine. The eleoptine is a hydrocarbon, C1oH3, isometric with spirits of turpentine, and distils at +175° C. The stearoptine is an oxygenized hydrocarbon C1oH12O2, isomeric with valerol, which distils at + 210° C., and is converted by oxidation into valerianic acid.

The chemical composition of lupuline proves the richness of its principles, for analysis has found in it the following:

In therapeutics, lupuline plays an important part, but the properties of the etherized narcotic extract, and those of a crystalline acid, in very bitter silky needles, which might be called humulin, have never been experimented on, and would probably be found powerful substitutes for opium and quinine.

The bitter substance of hops is a yellow solid matter, not very soluble in water, easily soluble in alcohol, less soluble in ether; it is odourless and of a very bitter flavour; has a feeble tendency to combine as easily with the metallic bases as with the acids. The resin of hops may be obtained pure by the action of boiling water. In the pure state this resin is free from all bitter flavour, it is insoluble in water; but is, on the contrary, very soluble in alcohol and in ether. The resin of hops has been the object of research by Vlaanderen. He treated the hop dust with boiling alcohol, then filtered it, added a considerable quantity of water, and evaporated it. In the yellow, cloudy liquor a soft resin of a dark brown colour is thrown down; this is separated from the liquor, again dissolved in alcohol, filtered, once more mixed with a large quantity of water, and evaporated, for the purpose of separating as much as possible by this evaporation

the oil which remains adhering to the resin. The same treatment is recommended several times, and continued until the resin has lost all trace of bitterness.

The etherized oil of hops is a yellow oil, obtained, it is said, in the proportion of 2 per cent. from hop dust by distillation. I have, however, never seen it obtained in such a quantity. The resin retains moreover a very large quantity of oil. This volatile oil is more or less soluble in water, it easily dissolves in alcohol and in ether. Its specific weight has been found = 0.908.

Way and Ogston on the one hand, and Hawkhurst on the other, have determined by analysis the constituent inorganic parts of hops. Watts and Nesbit have also effected the determination of them.

The following are their respective analyses:

It is chiefly to its bitter principle that the physiological action which hops exert is generally due; this action has

been compared to that of opium, and a narcotic power is generally attributed to hops, but I do not find sufficient reasons for this assertion.

In 1863 Lermer suggested the presence of a peculiar alkaloid in hops. Griessmayer's recent experiments seem to prove the existence of a peculiar volatile alkaloid, which he named lupulina. The concentrated aqueous decoction of ten pounds of hops was distilled with potassa or with magnesia, the distillate neutralized with muriatic acid, evaporated to dryness, treated with cold absolute alcohol, to remove sal-ammoniac, the alcoholic liquid heated to boiling, and evolved, when much muriate of trimethylamina crystallized. The filtrate evaporated in a water-bath, and finally spontaneously, the residue redissolved in water, in a narrow cylinder, agitated with potassa and ether, and the ethereal solution evaporated spontaneously. The remaining alkaline liquid had a peculiar odour, reminding of conia, and a cooling but not bitter taste. It soon separated in small crystals, and finally solidified completely. Other experiments proved that some kinds of hops contain no trimethylamina, and finally, also, that the substances present in hops go into beer.