4383. To Detect Arsenic in Colored Paper

4383.    To Detect Arsenic in Colored Paper. Take a fragment of the paper and put it into a solution of ammonia. If arsenic be present the liquid will assume a bluish color. In case a further test is required, pour a little of the ammoniacal solution on crystals of nitrate of silver, and arsenic, if present, will show itself by leaving a yellow deposit on the crystals. As arsenic is used in coloring all qualities of paper, from the cheapest to the costliest, a knowledge of this test will be of service.                         

4384. To Detect Gum Arabic in Gum Tragacanth

4384.    To Detect Gum Arabic in Gum Tragacanth. Make the gum into a clear mucilage, and filter carefully; pour strong alcohol upon it, and if it retains its solubility and transparency, no gum arabic is present, but if it becomes opaque, or deposits a powder at the bottom, it contains gum arabic or some similar substance.

4385. To Test Slates

4385.    To Test Slates. The test of a superior slate is its ability to remain unbroken, after being made red hot in a furnace and suddenly immersed in cold water while at that heat.

4386. To Test Silver or Gold

4386.    To Test Silver or Gold. For testing gold or silver, slightly wet the metal and rub gently with lunar caustic. If genuine gold or silver the mark will be faint; but if an inferior metal it will be quite black.

4387. To Test Mushrooms

4387.    To Test Mushrooms. The following are said to be tests of the wholesome-ness of mushrooms: Sprinkle a little salt on the spongy part or gills of the sample to be tried : if they turn yellow, they are poisonous ; if black, they are wholesome.

False mushrooms have a warty cap, or else fragments of membrane adhering to the upper surface; are heavy, and emerge from a vulva or bag; they grow in tufts or clusters in woods, on the stumps of trees, etc..; whereas the true mushrooms grow in pastures.

False mushrooms have an astringent, styptic, and disagreeable taste; when cut they turn blue; they are moist on the surface, and are generally of a rose or orange color.

The gills of the true mushroom are of a pinky red, changing to a liver color; the flesh is white; the stem is white, solid, and cylindrical.

Introduce a silver spoon, or an onion, into a vessel in which mushrooms are seething; if, on taking either of them out, they assume a dark, discolored appearance, the circumstance denotes the presence of poison existing among them; if, on the other hand, the metal or onion, on being withdrawn from the liquor, wears its natural appearance, the fruit may be regarded as genuine, and of the right sort.

Rub the upper skin with a gold ring or any piece of gold : the part rubbed, will turn yellow if it is a poisonous fungus.