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Test for Starch

The old and is white; the stem is white, solid, and cylin- , and cylinfamiliar test for starch is the blue color which drical.

Introduce a silver spoon, or an onion, into free iodine produces when brought in contact with it; but this is not the only reagent by a vessel in which mushrooms are seething; if, means of which we can detect the presence of on taking either of them out, they assume a starch in combination with similar bodies. dark, discolored appearance, the circumstance Bromine is nearly as good as iodine, and denotes the presence of poison existing among tannin is said, in some instances, to be better. them; if, on the other hand, the metal or A solution of 50 grains tannin in pint disonion, on being withdrawn from the liquor, tilled water will answer for making the test. wears its natural appearance, the fruit may A drop of this tannin solution will cause a be regarded as genuine, and of the right precipitate in extremely dilute solutions of sort. of sort. starch; the precipitate dissolves when warmed and reappears when the solution cools; and where the starch paste is old, the reaction is said to be more sensitive than that of iodine.

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. 4388. To Test the Hardness of Water. Hard water contains more or less carbonate of lime; the presence of this substance in waters is tested thus: Soap, or a solution of soap in proof spirit, mixes easily and perfectly with pure water, but is curdled and