BOOK XXXIII. XLi. 123-XLIV. 127 



fluidity. And as cinnabar and red-lead*^ are 

 admitted to be poisons, all the current instructions 

 on the subject of its employment for medicinal 

 purposes are in my opinion decidedly risky, except 

 perhaps that its apphcation to the head or stomach 

 arrests haemorrhage, provided that it does not find 

 access to the vital organs or come in contact with a 

 lesion. In any other way for my own part I would 

 not recommend its employment. 



XLII. At the present time silver is almost the 

 only substance that is gilded with artificial quick- 

 sih'er, though really a similar method ought to be 

 used in coating copper. But the same fraudulence 

 which is so extremely ingenious in every department 

 of life has devised an inferior material, as we have § 100. 

 shown. 



XLIII. With the mention of gold and sih'er rouchstotu 

 goes a description of the stone called the touch 

 stone, formerly according to Theophrastus ^ not 

 usually found anywhere but in the river Tmolus, 

 but now found in various places. Some people call 

 it HeracUan stone and others Lydian. The pieces 

 are of a moderate size, not exceeding four inches in 

 length and two in breadth. The part of these 

 pieces that has been exposed to the sun is better 

 than the part on the ground. When experts 

 using this touchstone, like a file, have taken with it 

 a scraping from an ore, they can say at once how 

 much gold it contains and how much siher or copper, 

 to a difference of a scruple, their marvellous calcula- 

 tion not leading them astray. 



XLIV. There are two points in which siher 

 shows a variation. A shaving that remains perfectly 

 white when placed on white-hot iron shovels is passed 



95 



