THE BIRMINGHAM REPORT ON THE PURIFICATION AND UTILISATION OF SEWAGE

1871 The Lancet  
from which we abstract the following :-It used to be believed that the different kinds of tea came from different species of the tea-plant; but the researches of Siebold, which have been confirmed by Fortune, have demonstrated that one and the same plant, Thea siensis, modified by climate, soil, and cultivation, furnishes all the tea which is in the market. Differences in the manner of preparing the leaves, and differences in the age of the leaves, also affect the quality of the tea; giving
more » ... the tea; giving rise to differences in the commercial article. Touching the influence of climate, it is worthy of note that the tea-plant will bear a wide range of climatic variation without suffering serious deterioration. The richness of the soil and the mode of cultivation, however, exercise a paramount influence on the quality of the tea. In this respect the tea-plant is like the tobacco-plant or the mulberrytree. Again, the method of preparation of the leaves is a comparatively trivial matter, whilst the age of the leaves is of prime importance. The youngest leaves give the best tea. Hence the explanation of the high price of choice varieties of tea. Choice teas consist of the youngest leaves, and to produce any considerable weight of young leaves a great number of plants is required; whilst the same weight of old or full-grown leaves is produced by a comparatively small number of plants. Zoller shows that the age of tealeaves may be ascertained by a chemical examination of the ash left on incinerating them. As the leaves grow they lose in potash and phosphoric acid, both absolutely and relatively, and gain in lime and silica. Examinations made at periods fourteen days asunder exhibit these phenomena with sufficient distinctness. In the practical examination of teas there is, therefore, a very simple and valuable rule: much potash and phosphoric acid together with little lime and silica means good tea, and the reverse bad tea. Having received a splendid specimen of tea grown in the Himalayas by a friend of Baron Liebig's, Zoller set to work I and made a chemical investigation of it, and obtained the ' ' following results. In 100 parts of the tea there were 4'95 parts of moisture, and 5'63 parts of ash. The ash contained in 100 parts-These numbers show very plainly high potash and phosphoric acid, together with low lime and silica. Zoller also made an infusion of this excellent specimen of tea, and communicates some interesting particulars. 100 grammes of the leaves was infused for a quarter of an hour in 3 litres of boiling distilled water, and the liquid poured off. Then a second 3 litres of boiling water was poured on the leaves and allowed to stand for a quarter of an hour. The 6 litres of infusion were subsequently evaporated to dryness, and the residue dried at 100° Cent. and weighed. This dry residue was found to amount to 36'26 per cent. of the original tea-leaves ; the remark being made, that in the above described operation the tea-leaves could not have been perfectly exhausted of soluble matter, and that the real proportion of soluble matter in the leaves must have been still higher than the experiment indicated. The tea-leaves in their ordinary, or air-dried, condition contained 5'38 per cent. of nitrogen. The percentage of thein in the leaves was found to be 4'94. Theobromine was also detected. A comparison of the analysis of the original tea-leaves with that of the tea-leaves after they have been exhausted with boiling water is given. After extraction, the percentage of potash in the ash is 7'34, whereas, before extraction, the percentage of potash was 39'22; showing how the analysis of the ash may be employed as a criterion to recognise adulteration of tea with spent tea-leaves. A point insisted upon in this interesting memoir is, that the greater proportion of the nitrogenous material in tea is not present in the form of thein. Peligot has shown that this other nitrogenous material is a protein compound, being a substance like casein. Tea is therefore, to some extent, food, and Zoller points out that 100 parts of Himalaya tea contain, in addition to the 4'94 parts of thein, 13'7 parts of protein compounds. large party of friends. The Chairman, in proposing the toast of "Success to the Club," remarked that to the vigorous manner in which this toast had on all previous occasions been received might in some measure be attributed the present satisfactory position of the Club. That position he considered, from his own daily observation, to have been attained by the exercise of economy and good management, a matter of no little congratulation to the members now that the Club had entered the sixth year of its existence, and had stood firmly whilst so many contemporary and more pretentious ones had collapsed. On the part of the Committee, he proceeded to state the reasons which had induced them to recommend that the Club should for the present be continued in Spring-gardens. Every effort had been made to secure a better house, and Dr. Marsh thought he had obtained this in Pall-mall East; when, however, that building came to be surveyed, it was found that it could not be rendered so commodious internally as the house in Spring-gardens, even although a large sum were expended in alterations. He referred with pleasure to the fact that many members who had retired from the Club were coming back, and he hoped that the new printed list now being preparedfor issue would show further additions, not only from old members returning, but also from new ones joining the Club.
doi:10.1016/s0140-6736(02)78246-9 fatcat:dqoqukjh3vcb3gu4c5idjg5xre