The following determinations of the percentages of ash in spurious leaves most used in the adulteration of tea, dried after the manner of tea, may serve to illustrate, the leaves being gathered towards the end of August:—
To these may be appended the determinations of Paraguay tea at 28 and the ordinary tea of commerce at 5.92 per cent.; while in Peligot’s analysis the average proportions of ash in true tea-leaves is given as follows:—
| Kind of Leaf. | Per cent. of Ash. | |||
| China | Tea, | 5.5 | ||
| Japan | “ | 5.5 | ||
| Java | “ | 5.3 | ||
| India | “ | 6.06 | ||
| Ceylon | “ | 6.06 | ||
Proving, as has been mentioned, that genuine tea-leaves as brought direct from the producing countries, or such as is a fair commercial article, does not yield less than 5, or sensibly more than 6 per cent. of ash on incineration. When the ash much exceeds 6 per cent. the first question to be considered is whether it is accidental or if the high yield of ash would be maintained if a larger quantity of the sample were incinerated. The composition of the ash of genuine tea-leaves has also been carefully studied, yielding on analysis the following constituents:—
This analysis is especially important, inasmuch as the tea which furnished the ash was of guaranteed purity, so that no question of the possibility of its sophistication could arise. On examining this analysis it will be observed that tea-ash contains a quantity of iron, also some manganese, the presence of manganese being so marked in tea-ash that on subsequent treatment of the ash with water a deep-green solution of manganate is obtained. Owing to this presence of manganese in tea-ash it also invariably evolves chlorine very perceptibly when it is treated with hydrochloric acid.
If the analysis of the tea-ash is referred to it will be noted that more than one-half of it should be soluble in water, so that for all practical purposes a complete analysis is not requisite, a determination of the ratio of soluble to insoluble parts of the ash being sufficient. Such a determination is made by boiling the ash several times with a little water, filtering and washing the residue in the filter, drying the precipitate, igniting and weighing it. The weight of the insoluble part of the ash may then be subtracted from the weight of the entire ash, in which manner both the percentage of the soluble and insoluble ash will be conveniently arrived at, in which case the following determination of the percentage of “soluble” and “insoluble ash” in 100 parts of spurious leaves and pure tea when completely dried will be of interest here:—
| Kind of Leaf. | Soluble Ash. | Insoluble Ash. | |
| Ash, | 3.19 | 7.48 | |
| Plum, | 5.66 | 4.24 | |
| Willow, | 4.16 | 5.18 | |
| Teas of commerce, | 3.55 | 2.47 | |
Proving that in spurious leaves the ratio of soluble or insoluble ash is very different from what it is in genuine tea-leaves, and that an ash of such composition cannot be very soluble in water.