Caustic, dry, burning.

     Corrosive, apt to corrode, to eat away, to penetrate.

How is the white powdered arsenic prepared?

By submitting the ore to a strong heat in a peculiar kind of furnace; this produces a dark grey powder, which is again heated in close iron vessels; this separates it from its impurities, and the arsenic is obtained in thick, solid masses; these, by exposure to the air, fall into a fine, white powder.

From what is the word Arsenic derived?

From a Greek word, signifying masculine—­powerful (as a poison).  Arsenic is dug out of mines in Saxony, near Goslar; in Bohemia; in England, in the Mendip Hills, in great quantities.  It has so strong a corrosive quality as sometimes to burn the hands and feet of the miners; it is a deadly poison for all known animals.  This poisonous mineral is not found native in its perfect form, being generally united with metallic ores.

What do you mean by Gems?

The word gem is used as a common name for all precious stones or jewels; they consist of the siliceous earths; and are much valued for their lustre, transparency, color, hardness, and rarity.  There are many different kinds of precious stones, each distinguished by its peculiar character.

How are they divided?

Into the pellucid gems, which are of great lustre, and extremely hard, as the diamond; the semi-pellucid, those which are not so transparent, but yet of great beauty; those of one color, as the emerald or turquois; and those variegated or veined with different colors.  Gems are sometimes found of regular shapes, with a natural polish, near the beds of rivers after great rains; these are of the pebble kind.  Sometimes they are found of irregular shapes, with a rough coat, in mines and the clefts of rocks.  Pearls, though not stones, are also ranked among the number of gems.

     Pellucid, clear as a drop of water.

     Semi-pellucid, half pellucid.

Describe the Diamond.

The diamond is a precious stone, the first in rank of all the gems, and valued for its beautiful lustre; it is the hardest of all stones, as well as the most valuable.  The most esteemed are colorless.  A diamond in its natural state as it comes out of the mine, and before it is cut, is called rough, because it has no brilliancy, but is covered with an earthy crust.  The diamond is the Adamant of the ancients; hence the expression “hard as adamant,” from its being the hardest substance in nature.  The cutting of diamonds is a work of labor, and requires great skill; the polishing is performed by a mill of simple construction.

Where are they mostly found?

In yellow ochreous earths; in mines; and likewise in torrents, which have torn them from their beds.  In former times, all the diamonds that were known were brought from the famous mines of Golconda, in Hindostan; the islands of Molucca and Borneo have also produced many valuable stones.  The diamond mines of Golconda are now so exhausted, that they are not thought worth the expense of working; these gems are now brought chiefly from Brazil, in South America.