Quantcast
  Due to a new server, slow response may occur for which we apologize Portal logo
Login/Register
Bactrian Gold Treasure from Afghanistan, coming soon....
/gemstones/agricola_textbook_of_mineralogy/page_033 - 2
 

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

Book I Minerals color, taste, odor , physical properties of gemstones and minerals such as emeralds, diamonds, rubies, sapphires 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
They distinguish one earth from another on the basis of utility and the different uses it offers to artisans. One is useful to farmers for nourish­ing and supporting plant life. Another is used by physicians, for example, Lemnian, Samian, and Armenian earths. Sculptors and potters use an­other such as the clay which is called creta by the potters. From this each fashions and shapes his works. Some are used by carpenters, for example red ocher which, for that reason, is called fabrilis. Painters have used Paraetonian, Melian, and other earths. Fullers use others such as Cimolian. Silversmiths use creta argentaria and many other earths are used by other artisans. This classification does not consider the true nature of earths and fails to distinguish sufficiently one earth from another. For example, Egyptian earth is both cultivated and used as a medicament. Red ocher (rubrica) is used by physicians, artisans, and painters. Cimo­lian earth is indispensable to fullers and physicians. Therefore, if we clas­sify earths as medical, potter's, artisan's, etc., we have to place the same earth in several species and genera. Since a substance cannot be trans­ferred from its own genus to another genus, medical earth, potter's earth artisan's earth, etc., cannot be species. While the mass of common people may distinguish one earth from another in this way, the expert in nat­ural history who must treat his subject correctly cannot use this classifi­cation. Some earths are classified as distinct species under genera accord­ing to the place or region where they are found and from which they take their names, such as Samian, Eretrian, Chian, and Selinusian. Although people sometimes add to the name certain characteristics in which one earth is known to differ from others, nevertheless the true character can­not be satisfactorily described in this manner.
First we must enumerate the principal differences of earths, next make clear to which class each earth belongs and the district from which the name is derived. It will be seen that I accept the common practice of giving locality names to earths because of the lack of another name and I believe that earths from one locality may be worthless while similar ones from another are valuable.
An earth, like other mineral substances, is either simple or composite. I do not say that simple earth is free from the other elements for scarcely any earth is found that does not contain a certain amount of water, fire, or air but it contains no other mineral or liquid juice. A composite earth, on the contrary, contains either one or several minerals or may have absorbed a liquid juice. For example, ochra is usually simple even though it has been subjected to fire and has a certain acrid quality, as is usually the case, while Melian earth is composite because it contains alum. Simple
21
Book I Minerals color, taste, odor , physical properties of gemstones and minerals such as emeralds, diamonds, rubies, sapphires Page of 251 Book II About different applications of earths (painting, medical) and their occurrences
Suggested Illustrations
Other Chapters you may find useful
Other Books on this topic
bullet Tag
This Page