The United States Tea Adulteration Act was passed by Congress in 1883. The enactment of this law was largely due to the exertions of prominent tea merchants, whose business interests were seriously affected by the sale (principally in trade auctions) of the debased or spurious article. It is stated in the official report of the United States Tea Examiner at New York City, that from March 1883 to December of the same year, 856,281 packages (about four millions of pounds) of tea were inspected, of which 7000 packages (325,000 pounds) were rejected as unfit for consumption. Since the enforcement in New York City of the Tea Adulteration Act, nearly 2000 samples of tea have been chemically tested under the direction of the author. The proportion grossly adulterated has been a little over nine per cent. But this does not apply to the total amount imported, since only those samples which were somewhat suspicious in appearance were submitted for analysis. As the result of the past two years’ experience in the chemical examination of tea, the prevailing adulterations were found to be of two kinds—the admixture of spent tea-leaves, and the application to the tea of a facing preparation. A natural green tea possesses a dull hue, and is but seldom met with in the trade; some Moyunes and uncoloured Japans (which latter, properly speaking, is not a green tea) being almost the only varieties not exhibiting the bright metallic lustre due to the facing process. The addition of foreign leaves was detected only in a few instances; the presence of sand and gravel occurred far more frequently. Apropos of the practical utility of Governmental sanitary legislation, it can be stated that, since the enforcement of the Adulteration Act, the tea imported into the city of New York has very perceptibly improved in quality.
Attempts in tea culture are being made in the United States of Columbia, S.A. A specimen of the prepared plant received by the writer, differed greatly in appearance from the Chinese and Japanese products. The leaves, which had not been rolled but were quite flat, possessed a light pea-green colour and a fine but rather faint aroma. An examination indicated that the tea, although very delicate in quality, was seriously deficient in body.
The analysis showed:—
| Per cent. | |
| Moisture | 6·70 |
| Total ash | 4·82 |
| Ash soluble in water | 1·62 |
| Ash insoluble in water | 3·20 |
| Ash insoluble in acid | 0·16 |
| Extract | 27·40 |
| Tannic acid | 4·31 |
| Theine | 0·66 |
| Insoluble leaf | 65·90 |
The following Tea Assay, while not including the determinations of all the proximate constituents of the plant, will, it is believed, in most instances suffice to indicate to the analyst the presence of spent leaves, mineral colouring matters, and other inorganic adulterations.
Theine (Caffeine), C8H10N4O2.—Contrary to the once general belief, there does not always exist a direct relation between the quality of tea (at least so far as this is indicated by its market price) and the proportion of theine contained, although the physiological value of the plant is doubtless due to the presence of this alkaloid.
The commercial tea-taster is almost entirely guided in his judgment in regard to the value of a sample of tea by the age of the leaf, and by the flavour or bouquet produced upon “drawing,” and this latter quality is to be mainly ascribed to the volatile oil.
The following process will serve for the estimation of theine:—A weighed quantity of the tea is boiled with distilled water until the filtered infusion ceases to exhibit any colour. The filtrate is evaporated on a water bath to the consistence of a syrup; it is next mixed with calcined magnesia to alkaline reaction, and carefully evaporated to dryness.
The residue obtained is then finely powdered, digested for a day or so with ether (or chloroform) and filtered, the remaining undissolved matter being again digested with a fresh quantity of ether, so long as any further solution of theine takes place. The ether is now removed from the united filtrates by distillation, whereupon the theine will be obtained in a fairly pure condition.