Of the various kinds of wheat which are imported at the present day into Rome, the lightest in weight are those which come from Gaul and Chersonnesus; for, upon weighing them, it will be found that they do not yield more than twenty pounds to the modius. The grain of Sardinia weighs half a pound more, and that of Alexandria one-third of a pound more than that of Sardinia; the Sicilian wheat is the same in weight as the Alexandrian. The Bœotian wheat, again, weighs a whole pound more than these last, and that of Africa a pound and three quarters. In Italy beyond the Padus, the spelt, to my knowledge, weighs twenty-five pounds to the modius, and, in the vicinity of Clusium, six-and-twenty. We find it a rule, universally established by Nature, that in every kind of commissariat bread[129] that is made, the bread exceeds the weight of the grain by one-third; and in the same way it is generally considered that that is the best kind of wheat, which, in kneading, will absorb one congius of water.[130] There are some kinds of wheat which give, when used by themselves, an additional weight equal to this: the Balearic wheat, for instance, which to a modius of grain yields thirty-five pounds weight of bread. Others, again, will only give this additional weight by being mixed with other kinds, the Cyprian wheat and the Alexandrian, for example; which, if used by themselves, will yield no more than twenty pounds to the modius. The wheat of Cyprus is swarthy, and produces a dark bread; for which reason it is generally mixed with the white wheat of Alexandria; the mixture yielding twenty-five pounds of bread to the modius of grain. The wheat of Thebais, in Egypt, when made into bread, yields twenty-six pounds to the modius. To knead the meal with sea-water, as is mostly done in the maritime districts, for the purpose of saving the salt, is extremely pernicious; there is nothing, in fact, that will more readily predispose the human body to disease. In Gaul and Spain, where they make a drink[131] by steeping corn in the way that has been already described—they employ the foam[132] which thickens upon the surface as a leaven: hence it is that the bread in those countries is lighter than that made elsewhere.