(1458) Detecting Anilin Red.

Manufacturer and Builder 1, 1876

Dissolve the canies in water, so as to have a red liquid, which can then be treated the same as the wine, lemonade, etc. The first thing is to add slowly liquid ammonia until the red color is destroyed and a dirty green replaces it. Then put the liquid in a long tube, closed at one end, and add about one-tenth of its bulk of ether, close the top with the finger, and shake it well, turning the tube repeatedly upside down; then let it settle for several minutes. The ether will soon float again, and if the liquid contains anilin, it will have absorbed its compound with ammonia. In order to find if this is so, the ether is poured off, or what is better, taken out with a pipet, and then the ammonia is neutralized with acetic acid, when the red color of the anilin will at once show its presence. If the liquid was not colored with anilin, the acetic acid will not cause the ether to become red. This simple test is so delicate that a one-millionth part of anilin can be detected, which corresponds to a single grain in about twenty gallons of liquid. Anilin being a very powerful coloring material, a very small quantity will communicate to liquids a very decided red color; but the addition of so small a quantity as the above, and which can be detected in the way indicated, will not cause much coloring in the liquid; so that if its red color is due to anilin, it is always present in larger quantities than this.

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