Beer as we understand it—modified, that is, by the introduction of the hop—was probably little known in England before the beginning of the sixteenth century. The varieties of beer at the present time are numerous. Some of them will be considered later on in detail. There are, however, only three principal types of fabrication,—the Belgian, Bavarian, and English. The beers of England, as of France, and for the most part of Germany, become sour by the contact of air. This defect is absent from Bavarian beers. So favourite a drink has, of course, been largely adulterated. Taste, colour, and smell are frequently due to unscrupulous falsifications. Bitterness is produced by strychnine, aloes, nux vomica, gentian, quassia, centaury, pyrethrum, absinthe, and many other ingredients. Colour is obtained by liquorice, chicory, and caramel; and flavour by other additions, which perhaps it is better not to particularize. Water, of course, is added to beer, as to most drinks, to enlarge the quantity and therefore the price. Potatoes are frequently a substitute for grain. Potash is introduced to give the much-desired “_head_,” chalk to diminish acidity, and chloride of sodium, or common salt, for the sake of what is called a _piquant_ flavour. It were well if these little eccentricities of the beer vendors had here their confine; but the sacred hunger for gold has added, alas! to these, virulent and narcotic poisons,[105] such as belladonna and opium, henbane and picric or carbazotic acid. In the city of London this kind of adulteration was formerly, it was fondly imagined, to some extent prevented by some ancient guardians, known as _ale-conners_, who had the right of entering all public-houses and tasting their ales. Only the most important beers of different countries are given in the following list, arranged alphabetically for convenience of reference:— AFRICA.