May i, 1890.] 
THE TROPICAL AGRICULTURIST. 
77S 
tion containing by exhaustive bohling the soluble con- 
stituents of the leaves. The process is simple, and it 
was found to give most concordant n suits when 
working on the same sample. The lead precipitate 
would contain some of the gallic acid and the oxalic 
acid if any were present, and therefore the weight of 
this precipitate was an excellent gauge of the astrin- 
gent prosperties present : the dried precipitates were 
found to have a composition averaging 50 per cent of 
plumbic oxide, a result agreeing with the constitution 
of gallotannio acid. The value of the present investiga- 
tion consists in the observance of the minutest detail 
in the process being carried out under exactly similar 
conditions, although applied to different samples. Tbe 
teas were all air dried, and contained from 5 to 6 per 
cent of moisture, the green leaves were dried in a 
water-oven previous to analysis, and the results were 
calculated upon the leaves containing 5 per cent of 
moisture. 
It will be observed in the above Table that the finest 
teasare those which oontain the most tannin, and there 
is a gradual declension of this principle as we ap- 
proach the Souchongs and Congous. The elevation 
does not appear to affect the amount of tannin as has 
been supposed. The Dodabetta Estate, the highest in 
the list, shows a smaller percentage of tannin, in the 
leaf than all the rest, but does not very much differ 
from the samples from Aratapara, sone 4,400 feet 
below : and in this respect there is very little to learn 
from the altitudes of the Ceylon teas. The highest 
tannin content ocours in Travancore tea of Seafield 
Estate, a tea of great fragrance, and considered to 
rank very high-class in the home market, and the 
Glenorchy broken pekoe of Ceylon, although oon- 
tainingl9 per cent of tannin, is one of Htha best priced 
teas of *he island. The determination of Nos. 9 and 10 
shows that the kind of shrub cultivated in India contains 
more or less tannin according to its original habitat. 
The coarse leaves, No. 11, were taken from the lower 
part of the bush, and were such as are never made 
use of in the factory. The green teasare very astrin- 
gent, and as they are made from the same estate as 
those above, it is evident that some of the astriogency 
is rendered insoluble in the process of manufacture. 
The amounts of tannin shown in the list, it must 
be remembered, are obtained by perfeotly exhausting 
the leaves, and do not represent the amount taken in 
domestic use. The infusion of the family tea-pot ex- 
tracts more or less tannin, according to the sample used 
and the time allowed for the leaves to soak in the 
boiling' water. The brokers' test of five minutes takes 
out one-fifth of tbeextraot, with a corresponding amount 
of ta' a n. The tea-pot infusion of ten minutes re- 
moves about one-third, fifteen minutes one-half, and 
twenty minutes two-thirds. The following experiments 
were made to show the amount extracted by infusing 
1 per cent of tea in boiling water for five and fifteen 
minutes : — 
Tannin. Extraoted Extracted 
in five minutes. in fifteen minutes. 
Per cent. Per cent. Per oent. 
A 1108 3-04 27 4 — — 
B 11-10 4-40 36-2 6 88 56'8 
C 12-32 4-28 34-7 — _ 
D 13-25 - — 7-88 59 5 
E 13-55 4-60 33-9 — — 
P 23-50 6-26 20-6 952 40 0 
The taunin is, undoubtedly, the source of the 
'• strength " of the tea, and the higher the tannin 
the richer the infusion, and the more of body will 
the Bample possess. Tannin is likewise a natural con- 
stituent of the ten, and is not amenable to suppression 
by higher cultivation, or by the ordinary processes of 
manufacture. The excellent qualities of Indian teas are 
accompanied by a higher percentage of this substance, 
and therefore must be treated as strong teas, either by 
diluting them with weaker Chinese or by taking a much 
smaller quantity when required for infus on in the tea 
pot. If a smaller amount of these strong teas is taken 
if good water is used for the infusion, if it is allowed 
to stand not longer than ten minutes we should not 
hear so muoh of the "deleterious ingredient" in this 
universally used beverage. 
Ootaoamund, India,— Ohemical A'evu, Deo. 27th, 1889, 
MANURES. 
Manure is not a mere incident of gardening, an item 
of small account, for upon an adequate supply of the 
substance depends whether the garden shall be a 
success or a failure — the manure heap is indeed the 
pivot of successful horticulture. 
The price of land, and its reutal value are now so 
great, that we can no loDger afford to follow the easy 
slip-shod practices of our early history, when a 
moderate crop gave satisfactory returns for the small 
amount of labour bestowed, the rental value being of 
small account. Our gardening of the nineteenth 
century, to be successful, must take a more intensive 
character, we must have large and early crops or uo 
profit ; small crops and late do not pay. 
The soil we cultivate may be capable of producing 
moderate results without much noticeable exhaustion 
but the soil that produces extraordinary crons mnJ 
have unusual natural fertility, or be handled with n 
common skill, and sustained by high-feeding 
This uncommon skill is afforded by the keen inr«lli 
gence of the horticulturist, and the hkh-feedi™ i« 
obtained by the judicious use of manure. ~ 
Object of Manobes. 
To manure the land is a very ancient practice It- 
was long supposed that the food of such a variety of 
plants, each with a different chemical composition as 
are found m the mixed growth of a garden ™ 
necessarily be different-almost as different 'as fh! 
properties of the plants themselves. But agricultural 
chemists have shown that the food of alfnSi 
very much alike ; though certain cksses cf plant 
owing to their economic requirements, must be SUD 
plied with specific substances in greater I,„1„ P 
than others. What is good for vegSles and ?ru?t is 
not always good for flowers, and this results not from 
the chemical difference between the constitute , e 
the ashes of the vegetables, the fruit, oTthe flow rs 
but from the mode of growth of the various pS 
and the particular object we have in view in theS 
cultivation. It is not so much the question of the 
composition of plants, as of the length of time the v 
may have for assimilating food from the so 1 ?hat is 
the important factor in a garden. 
The Identity op Plant Food. 
It has been said by Sir J. B. Lawes that if we 
thoroughly understood the action of the ordinary 
manures of the farm, and their influence upon our crops\ 
we should be in a better position to explain the effect 
of any particular ingredient in the artificial compounds 
sold in the market. r 
There are thirteen chemical elements in various 
forms of combination that are generally supposed to 
be concerned in plant-life. Some are furnished by 
he free hand of Nature in such quantity, that the 
horticulturist needs take no thought about their arti- 
nc al supply. 
For instance in the form of carbonic acid, carbon is 
contained in the air in sufficient quantity to sunnly 
any crop, since their are 28 tons of carbonic acid iu 
the air resting on every acre of the earth's surface. 
Oxygen and hydrogen are provided in inexhaustible 
quantity, and in ]ust the right proportions in the form 
of water. One necessary physical condition of plant- 
life is moisture, and m the presence of water the 
chemical requirements of growth so far as oxygen and 
hydrogen are concereed are fully met. The soil also 
furnishes several of the other mineral elements in 
sufficient amount. But there are three constituents- 
potash, phosphoric acid, and nitrogen-which are 
aptly said by Professor Kedzie to constitute the 
golden tripod of plant-life; these are not only indis- 
pensable for all growth, but their limited supply cor- 
respondingly limits all the other conditions of growth. 
In mauunal value they hold front rank, and upon 
their sufficient presence in the soil depends successful 
cropping, both in vegetables, fruit, and flowers. With 
a sufficient supply of these three ingredients in our 
soils in active form, there is no limit to production, 
save those imposed by the physical conditions of 
growth and season. 
