Ml 
We -cannot help sugpe&ting EODie Eu,:ious error iu 
the experiment of the Japanese soientist, for no 
tea analysis we havo ever seen has given a figure 
for tanisirj at all iipproaching 5 per cent in lowness. 
Indeed 10 per csot is a low proportion. Could the 
results tf the Japaaete experiments be at all 
depended on, it is obvious that due regulation ^nd 
even arrest cf the fermentiug or oxygenizing process 
would assume a new inipo-tanoe in the manufac- 
ture of tea The low ptrceutage of tannin in the 
Japanese Professor's experiment may, however, 
after all, be explained by the technical Etaiement 
as to "the conversion of large quantities of soluble 
tannin into insoluble phlobaphene," whatever that 
may be; It ia interesting to learn that the proeeea 
of retiring teas ("final firing " is the term in Ceylon) 
preparatory to packing in hermetically olosed pack- 
ages, improves the quality of the teas. 
RESEARCHES ON THE MANUFACTURE 
AND ANALYSES OF VARIOUS 
KINDS OF TEA. 
In a recent bulletin issued from the Imperial College 
at Tokyo, Komaba, Japan, is a very interesting account 
of some investigatious icto the values of variuus liinds 
of t a by ProfefSor Y. liozai, of which we give an 
a! F tract. 
Siooe good tea can only be prepared from very 
young leaves, liberally supplied with manure, there 
should be some difference in the composition of the 
leaves of young and of old, and p' rhaps also of maunrs-d 
and unmanured plants. Kusearches have shown that 
very material alterations take place in the tea leaf — 
partlculirly in its earlier periods of growth — thus : 
a. The percentage of water in the leaves conti- 
nually decreases from the spring np to the autumn, 
b. Crude protein and uiti ogeii-free extract regu'arly 
diminish, while crude fibre and ethereal extract in- 
crease proportionally. 
c. Theine diminishes gradually while tannin in- 
creases slightly. 
d. Subatanots soluble iu hot water gradually di- 
minish up to a certain period, and then increase 
slowly, 
«. As regards the quantity of ash, there is but 
a slight fluctuation throughout the year, but its com- 
ponents undergo a remarkable alteration : thus, there 
are a decided diminutiou of potash and phosphoric 
Boid, and a considerable enhancement of lime, mag- 
nesia, and iron ; furthermore, the quantities of soda, 
manganese, and sulphuric acid increase, while the 
percentage of Eiiici and chlorine remains nearly 
constant. 
Whether the age of the tea plant may h»ve 
some iuflueuoe upon the composition of the 
leaves is a subject not yet experimented upon, al- 
though the opinion that older plants produce 
better leaves prevails among tea-planters. Hence 
the practice of preferring — ^or, rather, selecting — tbe 
older plants for the preparation of a superior kind 
of tea : for instance, dew-dropa. It is, however, certain 
that cireful pruning and liberal manuring are necessary 
to obtain a fair crop of the leaves from the older plants. 
Still another factor which exerts an influence upon 
the composition of tea leaves is the peculiar method of 
screening the plants from light for a week or two just 
before the time of picking. By this means a peculiar, 
fine arcma is said to be conferred upon the tea, so that 
it is very easy, according to Japanese tea-drinkers, 
to tell beforehand whether or not the tea they drink 
originated Irom screened plants. It is, a priori, certain 
that there should be some difference in the composition 
of the leaves of normally-grown and those of screened 
plants. 
In order to solve the problem, a small plot in a large 
tea plantation was selected, where a moat uniform shoot- 
ing was observed ; n part of the plot was covered with 
■wooden friimes, so that the plants within were in com- 
plete darkneaB, while the other part was freely exposed 
to tbe light. Id this state the plants were kept for 
three weeks, after which time tha leaves in both parts 
were piol-.ed, when the leaves of the screened plants 
were found to have been cocipletely bleached. 
A partial analysis of these two specimens of haves 
gave the following figures (per cent, of dry matter). 
Grown in Grown ia 
darkneas liijht 
Theine 4-532 ... 3784 
Total niirogen ... 7-835 ... 6 915 
Tueine nitrogen ... 1-311 ... 1094 
A fpeciai trial showed that there was no practical 
difference iu th<j amount of tannin contained in the 
tott leaves, wi.other etiolited or green, It seems 
there"u..e, that the chief difference in the composition 
of these two apecimens of loaves hes in the quantities 
of theine contained. This difference i."!, however, not 
due to any new production of the said alkaloid in 
the darkened plants, but is simply caused by the 
formation of various organic substances, such as fibre, 
&o., in the leaves normally grown, and by the destruc- 
tion of nitrogen-free matters by the continuous res- 
piration iu tbe shaded plHnts. It is concluded that 
the tea originating from darkened plants acts more 
strongly upon the human frame than that from the 
normal plants. 
A large quantity of young tea leaves was next care- 
fully collected from a part of a large tea plantation 
where the most uniform shooting was observed. The 
leaves wera thoroughly mixed together and treated 
as follows : — 
1. 500 grs. wore immediately dried at 85° 0. 
2. 1,500 grs. were made into green tea. 
3. 1,500 grs. were manufactured into Dlaok tea. 
The following table gives the percentage oompo-iition 
of the dry substance of these three specimens. 
Crude protein 
Crude IXhre 
Eihereal extract 
Otlier nitrosen-free extract 
Ash 
Theine 
Tannin 
Soluble in hot water 
Total nitrogen 
Albuminoid nitrogen 
Theine nitrogen 
Amido nitrogen 
From this it will be seen that the loss of etherea 
extract is somewhat remarkable owing to a conversion 
of a part of the tannin into a form insoluble in efchert 
as a consequence, nitrogen-free ex tract shows a remark- 
able incrense. The fact that the loss of ethereal exiract 
in black tea is les? than in the green indicates the 
formation of organic acids aiid other components 
soluble iu ether during the fermentation of the 
leaves. Ash, too, suffers in both cases a slight 
loss, owing to the mechanical loss of the sap 
in which it is partly dissolved. The trifling loss 
of theine may also be attributed to the same source 
of loss rathtr than to its sublimation du'^i- g firing. 
The destruction chiefly concerns tannin, this happen- 
ing chiefly during the process of rolling and drying 
and, iu the case of black tea, fermentation is tha most 
energetic agent for tbe destruction of tauuiu. It is, 
indeed, true that it is very prone to altere.tions, eince 
even during the mere drying of tea leaves in the sun a 
slight but appreciable quantity of tannia is destroyed. 
The dimiuntion of extractive matter in black tea is 
most probably owing to the conversion of laige qua,nti- 
ties of soluble tannin into insoluble phlobaphene, and 
also the decomposition of organic matters by the orga- 
nised ferments duriofi the fermentation of leaves, 
while in the case of green tea, though a fraction of 
tannin is decomposed, it will not snffer so far-reaching 
a change as in that of blr.ck tea, and the decomposition- 
products thus formed may be soluble in water. 
Fruoa the foregoinpr it is evident that black tea Buf- 
fers more material alterations during preparation than 
green, since in the foi-mer the leaves are subjected to 
terment'xtion, while the manufacture of the latter 
couBista entirely of mere mechanical maDipulatious, 
I 
Original 
Green 
Black 
Leaves 
Tea 
Tea 
37-33 
37-43 
380-9 
10-44 
10-06 
10-07 
6.49 
5-52 
5-82 
27-86 
31-43 
35-.39 
4-97 
4-92 
4-93 
3 30 
3-20 
3-30 
12 91 
10 64 
4-89 
50-97 
53-74 
47-23 
5-97 
5-97 
6-22 
4-11 
3-94 
4-11 
0 98 
0-93 
0-96 
0-91 
1-13 
1-16 
