to distinguish fine gold and silver from their alloys, but when the technique of performing the test was improved and, as Theophrastus says here, a better kind of stone was discovered, this test was later developed into a method for determining the proportions of the precious metals in alloys. Though Theophrastus does not say so, the touchstone was undoubtedly used by the ancients to determine the proportions of gold and silver in their alloys. Pliny318 discusses the different proportions of silver in native gold found in different places, and this information probably originated from assays made with the touchstone. Moreover, since early Greek coins made of gold, silver, or electrum show relationships of weight and value, it is clear that a method of assaying gold and silver alloys must have been known even before the time of Theophrastus. Probably the refined or purified gold mentioned in this passage should be understood to include not only fine gold but also the alloys of gold combined with silver, especially those of high gold content. The analyses that have been made of ancient gold objects show that even the best ancient gold contained a sensible proportion of silver, and much of it contained a considerable proportion. The invariable presence of silver in their gold seems to have been recognized by the ancients, for Pliny319 remarks that all gold contains silver. The statement of Theophrastus may therefore be interpreted to include the use of the touchstone for assaying the alloys of gold combined with silver. The importance of this passage as evidence that the stater was the real standard of reference in the Greek system of weights has been pointed out by Professor Ridgeway.320
46. indications are obtained from the smallest possible weight. The smallest is the \rithe, and after that there is the \ollybos, and then the quarter-obol, or the half-obol; and from these weights the precise proportion is determined. The smallest proportion of metal that can be detected by the touchstone varies considerably and depends chiefly on the skill of the operator, the kind of alloy that is being tested, and the relative proportions of the metals in it. Though Theophrastus evidently
«8 XXXIII, 80.
319ΧΧΧΠΙ, 80.
320 W. Ridgeway, Numismatic Chronicle, Set. 3, XV (1895), 104-109.
