Silica | 11·30 | 9·30 | 27·75 Chlorine | 1·53 | 1·60 | 0·79 Potassa | 37·46 | 41·63 | Soda | 1·40 | 1·12 | Ferric oxide | 1·80 | 1·12 } | 16·00 Alumina | 5·13 | 4·26 } | Manganic oxide | 2·10 | 1·30 | Lime | 9·43 | 8·18 | 19·66 Magnesia | 8·00 | 5·33 | 11·20 Phosphoric acid | 12·27 | 16·62 | 15·80 Sulphuric acid | 4·18 | 3·64 | 1·10 Carbonic acid | 5·40 | 5·90 | 6·70 +-----------+-----------+---------- | 100·00 | 100·00 | 99·00 -----------------------+-----------+-----------+---------- “Tea dust” affords a high proportion of ash, sometimes amounting to 20 per cent., the composition of which is usually strikingly different from that of the ash of ordinary tea. It is deficient in potassa and phosphoric acid, and the amount of ash insoluble in water and acids is very excessive, as is shown by the following analysis, made by the author:-- _Ash of Tea Dust._ Per cent. Insoluble in acids 60·30 Alumina and ferric oxide 6·60 Lime 5·10 Magnesia 7·89 Potassa 11·00 Soda 2·51 Sulphuric acid 1·23 Chlorine 0·63 Phosphoric acid 4·73 ----- 99·99 Ash insoluble in water 80·00 PLATE II. [Illustration: TEA LEAVES.] The portion of ash insoluble in acids consisted of silica, clay, and soapstone, indicating that the ash of tea dust is largely composed of the mineral substances employed for “facing” purposes. The characteristics of the ash of unspent tea are the presence of manganic oxide, the large proportion of potassium salts present, and the solubility of the ash in water. The amount of ash in genuine tea ranges from five to six per cent. In the absence of exhausted leaves, it has been found that the finer sorts of tea afford a smaller proportion of ash than the inferior grades. It will be noticed that spent tea ash exhibits a marked increase in the proportion of insoluble compounds (silica, alumina, and ferric oxide), as well as a total absence of potassium salts.