Soapstone, gypsum, etc. - These substances, as has been stated, are detected by the ordinary methods of qualitative analysis, the particles to be examined being separated from the leaves by shaking in a cylinder with water.

Iron salts. - Sulphate of iron is said to be occasionally added to a tea to deepen the color of the infusion. Iron salts may be separated from the leaves or powder by cold dilute acetic acid. This solution is tested for iron by the usual qualitative methods.

Iron. - Metallic iron has been reported as sometimes present as an adulterant of teas. Iron may be separated from the finely powdered sample by a magnet. It may be distinguished from magnetic iron oxide by the separation of metallic copper from cupric salts.

1Pharm. Centralhalle, 1879, p. 258.

Magnetic oxide of iron. - Blyth1 states that ferruginous particles are sometimes found as adulterants of teas. These particles may be separated by a magnet. The author quoted (loc. cit.) states that he has found over 1 per cent of this ferruginous sand in teas, and that it must have been an adulterant.

Sand, par'tides of brick, etc. - A small amount of sand in a tea may be due to accidental causes while gathering the leaves, but any considerable quantity and particles of brick and similar matter can only be considered as having been added with fraudulent intent. These substances may be separated by shaking the leaves with water and collecting the sediment.

Copper. - The green color of some teas is popularly attributed to copper. There is little evidence to prove that copper has ever been employed for this purpose. Hassall2 made a large number of examinations of teas without detecting copper in a single sample. If copper is present in a tea a portion of the powdered sample added to ammonia water will impart a blue tint to the latter, the depth of the tint depending upon the amount of copper present.