THE TROPICAL AGRICULTURIST, 
August i, 1891 .I 
141 
Wo cannot help suspecting Eotr.o serious error in 
the experiment of Ihe Japuneso scientist, for no 
tea analysis wo have ever seen has pivon a hguro 
for, t; niii.'i at all approaching 5 per cent in lowness. 
Xni eeii 10 per cent is a low proportion. Could tho 
re-uUs tf the Japanese eifperimen.s be at all 
deptnJed on, it is obvious that due regulalion and 
oven arrobt o( the formetiting ut oxygenizing process 
would assume a new importance in the manufac* 
ture of te:, Ihe low percentage of tannin in the 
Japanoso Professor’s experiment may, however, 
axtor all, be explained by the technical statement 
an ^ “ the conversion of large quantities of soluble 
tar.nin into insolublq phlobaphene,” whatever that 
may be; It is iutc-rbsting to learn that the process 
of roiiriug teas (“final firing ” is the term in Ceylon) 
preparatory to packing in hermetically closed pack- 
ages, improves the quality of the teas. 
Rkseakchks on the manufacture 
and analyses of various 
JCINDS of tea. 
® biillotiu issued from the Imperial C’ollege 
at lokyo, Komaba, Jajian, is a very interesting account 
or some investigations into the values of vari .us kinds 
ot Ua by Professor Y. Kozat, of wliioh we give an 
abstract. 
Since good tea can only be prepared from very 
young leaves, liberally supplied with manure, there 
^nould bo some difference m the composition of the 
leaves of young and of old, and pf^rhaps also of manur^^d 
and unmanuc«‘d plants. Kescarches have shown that 
very material nltorationa take place in the tea leaf— 
particmirly m its earlier periods of growth— thus : 
a. ihe percentage of water in the haves conti- 
nually decreases from the spring np to the autumn. 
.'-' 5 ^do protein and nitrogen-free extract remi’arly 
immish, while crude fibre and ethereal extract in- 
crease proportionally. 
c. Theme diminishes trudually while tauniu in- 
creases slightly. 
d. Suhstttiicts solnhlo in hot water gradually di- 
niimsh up to a certain period, and then iuoreaae 
slowly. 
*. As regards the quantity of ash, there is but 
« sliglit fluctuation throughout the year, but its com- 
poDouta undergo a remarkable alteration : thu.s, there 
are a decided diminutiou of potash ami phosphoric 
aoid, and a oonsiderabte e’nhancorueut of lime, mag- 
nesia, and iron; furthermore, the quontitios of soda, 
maugauose, and sulphurio aoid iucrease, while tho 
percentage of silioi and chlorine roinaius nearly 
constant. 
Whether the ago of the tea plant may have 
some lefluence upon the composition ot tho 
net yet experimented upon, al- 
uough tho opinion that older plants produce 
nettcr loaves prevails among tea-planters, Henco 
tne praotice of preferring — or, rather, selecting — the 
c aer plants for tho preparation of a superior kind 
r dew-drops. It is, however, certain 
tn nkf *nd liberal manuring are ueoessary 
b am a lair crop of tho leaves from the older plants. 
factor which exerts an iutluenco upon 
he compo^iiion ot Ua leavea is tho pecnllar method of 
^ 1 ® p'snls from light for a week or two just 
Lute of p oking. By this means a peculiar, 
tine arema is said to ha contorted upon tho tea, so that 
Japanese toa-driukers, 
or nut Ihe Ua they drink 
originated from .sereeued plants. It is, „ wfon', certain 
la there hIiouM he some flifferei'c© iu tho composition 
otthe leaves of normally.gro^u and those of screeuod 
plants. 
'■*i® PfoWein, a small plot in a large 
planmtion was solpcted, where a most uniform shoot- 
was covered with 
plants within wore in com- 
tn ik while the other part was freely exposed 
he light. In this state the plants wsre kopt for 
three yveeits, after which time the leaves in both parts 
were picked, when tho leavea of the screened plants 
were found to have been completely bleached. 
A partial analysis of these two specimens of leaves 
gave the following figures (per ceut. of dry matter). 
Grown in Grown in 
darkness light 
Theino, 4-532 ... 3-784 
Total nitrogen ... 7-835 ... 6 045 
Theino nitrogen ... 1-311 ... 1-094 
A speoi'l trial showed that there was no practical 
difforenoo in ihu amount of tannin contained in the 
tea leaves, whetlier etijhted or green. It seems, 
therefore, that the ohief difference in the composition 
of these two speoimnus of leavea lies in the quantities 
of tbeiuo contained. This diSereuoe is, however, not 
due to any new pruduotion of the said alkaloid in 
tho darkened plants, but is simply caused by the 
formation of various organic aubstances, such as fibre, 
&o., iu tho leavis noimally grown, and by the destruc- 
tion of iiivcogen-freo matters by tho oontinuous res- 
piration iu tho shaded plants. It i.s ouncluded that 
the tea originating from darkened plants aota more 
strongly npon tho human frame than that from Ihe 
normal plants. 
A large quantity of young tea leaves was next care- 
fully collected from a pert of a large tea plantation 
where the moat uniform shooting was observed. The 
leavea were thoroughly mixed together and treated 
as follows 1 — 
1. 500 grs. were immediately dried at 85® 0. 
2. 1,500 gra. were made into green tea. 
8 . 1,500 gre. weco maunfaetured into black tea. 
The following table gives tho percentage oomposiiiou 
of the dry substance of these three speoimeus. 
Crude protein 
Crude fibre 
Kthoreal extract 
Other nitrogen-free extract 
Ash 
Thoiue ... . 
Tannin 
Soluble In hot water 
Total nitrogen 
Albumlm-id nitrogou 
Thelue nitrogen 
Atuido nitrogen 
Original 
Green 
Illaok 
Leaves 
Tea 
Tea 
37-«3 
37-43 
380-9 
10-44 
10-06 
10*07 
6.49 
5-62 
6-82 
27-H6 
81-43 
35-39 
4-97 
4-92 
4-93 
3 30 
3-20 
3-SQ 
12 91 
10 64 
4*89 
00-97 
53-74 
47*23 
5-97 
5-97 
d-22 
4-n 
3-91 
4-11 
0 96 
0-93 
0-9Q 
0-91 
1-13 
116 
From this it will be seen that the loss of etheroa 
extract is somewhat remarkable owing to a conversion 
of a part of Ihe tannin into a form insolublo in ethert 
as a cunaequenoe, nitrogen-froe extract shows a remark- 
able increase. ‘The foot that the loss of eth. real extract 
in black tea is lest than in the grt-en indii ites the 
tormatiuu of organic acids and other .umponents 
soluble iu otber during the fermentation of the 
leaves. Asb, too, suffers in both oases a slight 
loss, owing to the mechanical loss of the sap 
in which it is partly dissolved. The trifling loss 
of tbeine may also be attributed to the same source 
of loss rathir than to its sublimation during firing. 
The destruction cliiclly concerns tannin, this happen- 
ing chiefly during the process of rolling and drying 
and, in tho case of black tea, fermentation is the most 
euergetio agent for the ilastruotion of tannin. It is, 
indeed, truo that it is very prone to altoratione, since 
even during tho mere drDng of tea loaves in the sun a 
slight but appreoiaOlb quantity of tsuuiu is destroyed. 
The dimioulion of oxt-activo matter iu black tea is 
must probably owing to the cunversiou ot large quanti- 
ties of soluble tanciio into insoluble phlobaphene, and 
also the deoonipesiliou of organic matters by the orga- 
nised ferments during the ferraeotation of leaves, 
while iu tho case of green tea, though a fraction of 
tannin is vlooomposed, it will not s.-ffer so far-reaching 
a ohan;re as in that of black tea, and the decomposition- 
products thus formed may be soluble in water. 
From the foregoing it is evident that black tea snf. 
fers more material alterations during preparatiou thau 
green, since in the former tho leavas aro eubjeoted to 
fermentation, while the manulaoture of the latter 
oonsists entirely of mere meohanioul manipulations. 
