BOOK XII

1 REVIOUSLY I have dealt with the methods ofseparating silver from copper. There now remainsthe portion which treats of solidified juices ; andwhereas they might be considered as alien to thingsmetallic, nevertheless, the reasons why they shouldnot be separated from it I have explained in thesecond book.

Solidified juices are either prepared from watersin which nature or art has infused them, or they areproduced from the liquid juices themselves, or from stony minerals. Sagaciouspeople, at first observing the waters of some lakes to be naturally full of juiceswhich thickened on being dried up by the heat of the sun and thus becamesolidified juices, drew such waters into other places, or diverted theminto low-lying places adjoining hills, so that the heat of the sun shouldlikewise cause them to condense. Subsequently, because they observed thatin this wise the solidified juices could be made only in summer, and thennot in all countries, but only in hot and temperate regions in which it seldomrains in summer, they boiled them in vessels over a fire until they began tothicken. In this manner, at all times of the year, in all regions, even thecoldest, solidified juices could be obtained from solutions of such juices,whether made by nature or by art. Afterward, when they saw juicesdrip from some roasted stones, they cooked these in pots in order to obtainsolidified juices in this wise also. It is worth the trouble to learn the pro-portions and the methods by which these are made.

I will therefore begin with salt, which is made from water either saltyby nature, or by the labour of man, or else from a solution of salt, orfrom lye, likewise salty. Water which is salty by nature, is condensed andconverted into salt in salt-pits by the heat of the sun, or else by the heatof a fire in pans or pots or trenches. That which is made salty byart, is also condensed by fire and changed into salt. There should be asmany salt-pits dug as the circumstance of the place permits, but there shouldnot be more made than can be used, although we ought to make as muchsalt as we can sell. The depth of salt-pits should be moderate, and thebottom should be level, so that all the water is evaporated from the salt bythe heat of the sun. The salt-pits should first be encrusted with salt, sothat they may not suck up the water. The method of pouring or leadingsea-water into salt-pits is very old, and is still in use in many places. Themethod is not less old, but less common, to pour well-water into salt-pits, aswas done in Babylon, for which Pliny is the authority, and in Cappadocia,where they used not only well-water, but also spring-water. In all hotcountries salt-water and lake-water are conducted, poured or carried intosalt-pits, and, being dried by the heat of the sun, are converted into