January i, 1892.] THE TROPICAL AGRICULTURIST. 
I also bear of a valuable Mexican silver mine, which 
will shortly be placed on the market ; the argentiferous 
i deposits cover an extensive area, and are unusually 
I rich in ore. 
A valuable West-End business, possessing a practical 
monopoly, is also to be converted into a Limited Com- 
■ pany, as the fortunate owner has already realised a 
a large fortune by the business, which is still increasing, 
I and is only converting it into n company to lesson his 
own individual labour, and to provide for his family. 
This should afford a far safer investment than even 
I sapphires or rabies. 
TEA ANALYSIS. 
As an instance of the difficulties to be met with by 
the unscientific enquirer after truth in the matter 
of tea analysis, we give the following extract from 
the Analyst : — 
" Examination of China Teas. By P. Dvorkovitch, 
J own. of Anal, anid Applied Chem., Vol.V., p. 345. — 
The author estimates the amount of theiue as follows 
—10 grammes of tea are carefully ground and 200 c.o. 
boiling water are poured over it. Five minutes later 
the infusion is decanted. This operation is repeated 
three times. The tea is then boiled twice with 203 
c.o. water eich time, so that the water is not coloured, 
I or but slightly so. The extract thus obtained is diluted 
to one litre. A portion of this extract is washed with 
petroleum ether three times, in order to remove the oil 
and the brown substance found in tea, to which Mulder 
has already called attention. Then 600 cc. of this 
aqueous infusion, corresponding to 6 grammes tea, are 
taken, washed with petroleum ether, 100 o.c. of a 
I caustic baryta solution, containing 4 grammes in 100 
o.c. are added to it, well shaken and filtered im- 
! mediately from the precipitate obtained. 583 grammes 
of the filtrate, corresponding to 5 grammes of tea, are 
then mixed with 100 c.o. of 20 per cent salt solution 
and the mixture, shaken with chio oform three times, 
! about 400 grammes chloroform being used in all. The 
! solvent is then removed by distillation, and the residue 
i of theine dried at 100° C. Absolutely white theine is 
! obtained in beautiful needle-shaped crystals. 
I The washing with petroleum ether is neoes- 
'i gary, first, for the removal of the ethereal oil, and 
I next for that of the brown substance alluded to. 
' One and the same tea, washed and not washed 
with petroleum ether, showed a difference of 0.6 p c. 
i in its contents of theine. This method gives higher 
j results than that of Peligot, Mulder, or J. Bell. AH 
; methods based on Mulder's principle, viz., on the boil- 
ing of the tea with magnesia or lime, give results which 
1 are two low, on account of the partial destruction of 
f the theine with evolution of ammonia. 
" The preliminary fermentation, to which all black 
teas are subjected, destroys a varying proportion of the 
tannin. The quality of the tea, to a very great extent, 
depends upon the method of fermentation, the astrin- 
' gency not only being lessened thereby, but the aroma 
' being developed. The author worked out a method ap- 
' plicable to the d termination of the tannin and to its 
j products of fermentation, based upon the Loewenthal 
principle. A solution of tea, 10 grammes to the litre is 
made precisely as above described, 40 o.c. being diluted 
with 500 o.c. of water, and titrated with permanganate, 
with indigo carmine as indicator. 80 cc. of the tea 
solution are then mixed with 20 o.c. of caustic baryta 
containing 4 grammes. In 100 cc. the precipitate is 
filtered off and 50 cc. titrated with permanganate. 
The quantity of permanganate thus expended indicates 
the quantity of the products of the decomposition of 
tannin ; that is to say, the degree of fermentation to 
which the leaf was subjected. The longer the fcr- 
mentntion lasted, the more of these products. The 
percentage both of tanniu and the products of fermen- 
; tation are calculated from the oxalic aoid standard 
of tho pormangnniito solution, C3 grammes of oxalic 
acid oorrespondiug, according to tho author to 31'3 
grammes of tauuio, and not to 41'2, as found by 
Ncnbauer. 
" Twonty-niuo samples of tea were examined. The 
best qualities ooutaiucd the Urgoat amounts oi tbeiuu. 
This was manifested more strongly when the ratio 
of theine to the total amount of tannin and producta 
of fermentation was calculated. The theine varied 
from 2-14 in the cheapest, to 3-21 in the best tea ; 
the percentage of theine to total tanniu from 16'0 
to 24-52.* 
'■It need hardly be added that these deductions are 
in direct contradiction with those of many other 
observers." 
The last sentence is evidence of the uncertainty o( 
chemical deductions. — H. and C. Mail, Nov. 6th. 
^ 
CAN WE MAKE IT RAIN. 
The October number of the North American 
I Review oontaina two articles under the somewhat 
startling heading " Can we make it rain ? " The 
first is by General Eobert G. Dyrenforth, who has 
been attempting, and, as he believes, successfully 
attempting, to produce rain in districts afHioted 
with drought, by means of dynamite and other 
explosives. In the second article, Professor Simon 
Newoomb, the eminent astronomer, tries to drown 
General Dyrentorth'a arguments and conclusions in 
a cold shower of sarcasm. It has been frequently 
noticed that heavy cannon-firing has been followed 
by rain. In 1870 an American author, Mr. Edward 
Powers, published a book entitled " War and the 
Weather," in which it is stated that 198 battles 
of the Civil War, including every battle of im- 
portance, were immediately followed by drownpours. 
Results such as these, however, need very careful 
criticism before any definite conclusion can be 
drawn from them, and it occurred to several dis- 
tinguished men in the United States that the 
question was one of sufficient importance to deserve 
experimental investigation. A scheme promoted in 
1874 by General Garfield, General William Sherman, 
and others fell through owing to lack of funds, But 
in 1890 the Hon. C. B. Farwell succeeded in ob- 
taining from the Department of Agriculture and 
the American Government a sum of 9,000 dola. 
for a new project, which did not involve, like the 
former, the expense and difficulty of transporting 
a large number of cannon from the coast to a 
rainless district. General Dyrenforth was asked to 
take charge of the investigations, and he has now 
published the details of the first experiments made 
under his direction. 
" On the 5th day of August," says General 
Dyrenforth, " our party arrived at Midland, Texas, 
a small station on the Texas and Pacific Railway, 
situated on the Llano Estacado, or Staked Plains, 
in a region which had been suffering from a 
severe drought of several months' duration, and a 
lack of good rains for several years. The party 
made its headquarters at a point twenty-five miles 
from Midland, in the midst of a dry prairie bear- 
ing little vegetation but scattered clumps of grass 
and low mesquite bushes, with here and there a 
cactus. The plan of operations was somewhat as 
follows : — Three lines were to be formed, each some 
two miles in length, and placed about one half 
mile apart. The first line to the windward was 
to consist of a large number of ground batteries, 
where heavy charges of dynamite and raok-a-rock 
powder would be fired at frequent intervals. The 
next line to the rear was to consist of a number 
of kites flown to a considerable height by eleotrio 
wired, bearing dynamite cartridges suspended from 
them, to be tired high in the air. The third and 
main line was to consist of explosive balloons, 
* So that the proportion of tanniu in tea containing 
3 21 per cent of theine would be about 1' per cent 
-Ku, T.A. 
