Manufacturer and builder 5, 6 tai 7, 1869
In addition to thee common harmless method of adulterating milk by means of diluting it with water, a method has been discovered supplementary thereto, intended to conceal any excessive watery dilution, namely, by adding a solution of dextrine and also of boiled starch. This is easily discovered with iodine water, which colors the milk blue when the smallest quantity of dextrine or boiled starch is present. The principal methods of adulterating tea leers and in Europe are only intended to give it a better appearance. This is effected by means of powdered gypsum and Prussian blue. Lately the more common, cheaper qualities have been mixed with the dried refuse leaves from the large tea-pots of hotels, restaurants, and boarding-houses, which are secretly bought up by the parties interested. The first method of adulteration is easily discovered by the sediment, when the tea is prepared in the usual way; the last by the appearance of the leaves and the weakness of the do coction. The Chinese have lately outstripped us altogether in this art. They now casks a cheap article of tea out of sand, earth, and gum, which are so treated as to take on the appearance of dried and rolled leaves. The tea flavor is communicated by means of the refuse powder of tea. The black variety is imitated by coloring with lampblack; the green, with Prussian blue and powdered gypsum. The simplest method of detecting this fraud is to burn the tea. Genuine, unadulterated tea never leaves more than five per cent of ash; the adulterated kind in question leaves from forty to fifty per cent.
Annatto, a substance now chiefly used for dyeing silk and cotton orange-yellow, and also for coloring butter and cheeses, is sometimes greatly adulterated with red ochre, powdered bricks, and colcothar. Upon burning some of this adulterated substance, these admixtures are of course detected in the asters; a sample recently analyzed had been adulterated with thirty-four parts of water, twenty-two of oxide of iron, and thirty-six of sand and silicates.