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Book II About different applications of earths (painting, medical) and their occurrences

Book II About different applications of earths (painting, medical) and their occurrences Page of 251 Book II About different applications of earths (painting, medical) and their occurrences Text size:minus plus Restore normal size   Mail page  Print this page
BOOK II
33
principal city of the island. This earth is moderately unctuous but whether it is dense or not I cannot say as nothing has been written about this property. There are two varieties, the white used by painters, the gray used by physicians. The gray variety has a variable hardness and phy­sicians prefer the softest. Although other earths are used by copper work­ers to mark the copper with a violet line, according to Galen, this one makes a better line than Lemnia earth and yet it does not eat the metal. After the line is washed off only a very slight trace remains. An unctuous green earth similar to Eretria is found in a limestone quarry in Hanover and is ground for use as a pigment by copper workers although the color after grinding is an intense bluish gray.
Pnigitis earth takes its name from the village of Pnigeus in Egyptian Libya. According to Dioscorides it has a color similar to Eretria earth which we know to be gray. On the other hand Galen and those who follow him, for example, Paulus Aegineta, describe it as black. It is unctuous, dense, soft, black, sometimes astringent, sometimes acrid. It is certainly unctuous since Galen describes it as no less glutinous than Samia earth and if anything even more so. Dioscorides says it will stick to the tongue with such force that it will hang from it. We know it to be dense since Dios­corides writes that it contains solid lumps and cools the hand consider­ably when held in it. Since it has properties similar to those of Cimolia earth we known it must be variable, namely, some must be astringent and cooling, some acrid and warming. Dioscorides describes it as somewhat weaker than Cimolian.
Not dissimilar to the above is an earth known as black chalk. This is found in Germany near a town which takes its name from waters (Cologne). It is also similar to red ocher and is used by the carpenters in that vicinity in the place of ocher. There are two varieties, one that is soft and makes a line when dry, one that is hard and makes a line when moistened. They are moderately unctuous, porous, black, acrid, and both hard and soft. Each variety is also found at Hildesheim, Saxony, in the moat of the north wall.
The earth the Greeks call μίλτοs is red and for that reason is called red earth or red ocher. It is found in gold, silver, copper, and iron mines and was known to Theophrastus. It is sometimes found in pure veins. At one time the best was mined at Cappadocia and taken to Sinope. An inferior variety was found on Lemnos, as I have said, and was one of the Lemnia earths. This material is found on a hill and is the red ocher used by ar­tisans. Ocher is also found in Egypt, Africa, and the Balearic Islands. Dios­corides calls the African earth "Cartaginian ocher." Today it is found in Greater Germany in ore veins and in veins of pure ocher, for example, near the town of St. Wendelin. All red ocher which adheres to rock is of a uniform color and therefore better than other varieties. That which does not adhere to rock and has congealed in lumps usually has variegated colors. There are three varieties of the latter, a deep red, a light red, and one of an intermediate color. The ocher Theophrastus calls αυτάρκη i.e.,
Book II About different applications of earths (painting, medical) and their occurrences Page of 251 Book II About different applications of earths (painting, medical) and their occurrences
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