[ 191 ]
LXXX. All theſe Stones are found in the River [1]Tmolus; their Texture is ſmooth, and like that of Pebbles; their Figure broad, not round; and their Bigneſs twice that of the common larger Sort of Pebbles. In their Uſe in the Trial of Metals, there is a Difference in Power between their upper Surface, which has lain toward the Sun, and their under, which has been to the Earth, the upper performing its Office the more nicely; and this is conſonant to Reaſon, as the upper Part is the dryer; for the Humidity of the other Surface hinders its receiving ſo well the Particles of the Metals: For the ſame Reaſon alſo it does not perform its Office ſo well in hot Weather
- ↑ The true Lydius was originally found only in this River, afterwards in many other Places; and at preſent is very plentiful in many of the larger Rivers of Germany, This Author gives
Metals; Chryſites, from its particular Efficacy in Trial of Gold; and Coticula, becauſe it was generally formed, for Conveniency, into the Shape of a ſmall Whetſtone. We are not to ſuppoſe, however, that this Stone alone ſerves for that Purpoſe; in Italy a green Marble, called there Verdello, is now generally uſed in its ſtead; and in moſt other Places the Baſaltes, a black Marble, found in regularly ſhaped Columns, many placed together, as in Ireland, where a Quantity of it is called the Giants Cauſeway.
