2nd. Substances added in order to produce an artificial appearance of strength to the tea decoction, catechu and other bodies rich in tannin being mainly resorted to for this purpose.
3rd. The imparting of a bright and shining appearance to an inferior tea by means of various colouring mixtures or “facings,” which operation, while sometimes practised upon black tea, is far more common with the green variety. This adulteration involves the use of soap-stone, gypsum, China clay, Prussian blue, indigo, turmeric, and graphite. The author lately received from Japan several samples of the preparations employed for facing the tea in that country, the composition of which was shown by analysis to be essentially as follows:—
- Magnesium silicate (soap-stone).
- Calcium sulphate (gypsum).
- Turmeric.
- Indigo.
- Ferric ferrocyanide (Prussian blue).
- Soap-stone, 47·5 per cent.; gypsum, 47·5 per cent.; Prussian blue, 5 per cent.
- Soap-stone, 45 per cent.; gypsum, 45 per cent.; Prussian blue, 10 per cent.
- Soap-stone, 75 per cent.; indigo, 25 per cent.
- Soap-stone, 60 per cent.; indigo, 40 per cent.
The “facing” or “blooming” of tea is often accomplished by simply placing it in an iron pan, heated by a fire, and rapidly incorporating with it one of the preceding mixtures (Nos. 6, 7, 8, or 9), in the proportion of about half a dram to seven or eight pounds of the tea, a brisk stirring being maintained until the desired shade of colour is produced.
Some of the above forms of sophistication usually go together;—thus exhausted tea is restored by facing. The collection of the spent leaves takes place in China. Much of the facing was, until about three years since, done in New York city, and constituted a regular branch of business, which included among its operations such metamorphoses as the conversion of a green tea into a black, and vice versâ.
According to James Bell,[5] the composition of genuine tea is as follows:—
| Congou. | Young Hyson. | |
| per cent. | per cent. | |
| Moisture | 8·20 | 5·96 |
| Theine | 3·24 | 2·33 |
| Albumin, insoluble | 17·20 | 16·83 |
| „ soluble | 0·70 | 0·80 |
| Extractive, by alcohol | 6·79 | 7·05 |
| Dextrine, or gum | .. | 0·50 |
| Pectin and pectic acid | 2·60 | 3·22 |
| Tannin | 16·40 | 27·14 |
| Chlorophyll and resin | 4·60 | 4·20 |
| Cellulose | 34·00 | 25·90 |
| Ash | 6·27 | 6·07 |
| 100·00 | 100·00 |
The ash of samples of uncoloured and unfaced tea, and of spent tea analysed by the author, had the following composition:—
| Oolong (average of 50 samples). | Japan. | Spent Black Tea. | |
| per cent. | per cent. | per cent. | |
| Total ash | 6·04 | 5·58 | 2·52 |
| Soluble in water | 3·44 | 3·60 | 0·28 |
| Per cent. soluble | 57·00 | 64·55 | 11·11 |