January i, 1892.] 
THE TROPICAL AQRIOULtURIST. 
45 1 
1 alio hear of « valuable Mezioan eilvor m’uu, which 
will shortly be placed on the market ; the argentiferous 
deposits cover an extensive area, and are unnsuall; 
rich in ore. 
A valuablo Weat-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 lar^e fortune by the business, which is still increasing, 
and IS only converting it into a eompsoy to lesson bis 
own individual labour, and to provide for his family. 
This should all'ord a far safer investment than oven 
sapphires or rubies. 
TEA ANALYSIS. 
As an instance of the difficulties to be met with by 
the unaoientido enquirer after truth in the matter 
of tea analysis, we give the following extract from 
the Analyst : — 
‘‘ Examination of China Teas. By P. Dvorkovitch. 
Joum. of Anai- and Applied C'Asm., Vol. V., p. 346. — 
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 minntes later 
the infusion is decanted. This operation is repeateil 
three times. The tea is then boiled twice with 203 
0 . 0 . water etch time, so that the water is not coloured, 
or bnt slightly so. The extract thns obtained is diluted 
to one litre. A portion of this extract is washed with 
petroleum other three times, in order to remove the oil 
and the brown substance fonnd in tea, to which Mulder 
has alrea ty called attention. Then 600 c.o. of this 
aqueous infusion, corresponding to 6 grammes tea, are 
taken, washed with petroleum ether, lUO c.o. of a 
oaustio baryta solution, containing 4 grammes in 100 
o,c, are added to it, well shaken and filtered im- 
mediately from the precipitate obtained. 633 grammes 
of the filtrate, corresponding to .5 grammes of tea, are 
then mixed with 100 c.o. of 20 per cent salt solniiou 
and the mixture, shaken with chlo'oform three times, 
about 400 gramme.s chloroform being used in all. The 
solvent is then remove.! by distillation, and the residue 
of tbeine dried at 100° C. Absolutely white tbeine is 
obtained in bcantiful neodle.shaped crystals. 
“ The washing with petroleum other is neoes- 
dary, first, for the removal of the ethereal oil, and 
next for that of the brown substanoe allndod to. 
One and the same tea, washed and not washed 
with petroleum ether, showed a difierenoe of 0.6 p o. 
in its contents of theine. This method gives higher 
results than that of Peligot, Mulder, or J. Bell. All 
methods based on Mulder’s principle, viz., on the boil- 
ing of the t-a with magnesia or lime, give results which 
are two low, on aocount of the partial destruction of 
the tbeine with evolution of ammonia. 
“ The preliminary fermentation, to which all black 
tens are subjected, destroys a varying proportion of the 
tannin. The quality of the tea, to a very groat extent, 
depends upon the method of fermentation, the astrin- 
gency not oniy being lessened thereby, but the aroma 
being developed. The anther worked out a method ap- 
plicable to the d termination of the tannin and to its 
produote of fermentation, based upon the Loewenthal 
principle. A solution of tea, 10 grammes to tbe.litre is 
made precisely as above described, 40 o.o. being diluted 
with 600 c.o. of water, and titrated with permanganate, 
with indigo carmine as indicator. 80 o.c. of the tea 
solution are then mixed with 20 o.o. of oaustio baryta 
containing 4 grammes. In 100 o.o. the precipitate is 
filtered off and 50 c.o. 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 fer- 
mentation lasted, the more of these products. The 
percentage both of tannin and the products of fermen- 
tation are osloulated from the oxalio acid standard 
of the permanganate solnticn, 63 grammes of oxalio 
acid eorrespondin^, according to the author to 31’3 
grammes of tannin, and not to 41'2, as found by 
Nenbauer. 
“ Twenty-nine samples of tea were examined. The 
bwt qualities contained the largest amounts of theine. 
This was manifested more strongly when the ratio 
of theine to the total amount of taanin and products 
of fermentation was calculated. The theine varied 
from 2' 14 in the cheapest, to 3'21 in the bust tea t 
the percentage of theine to total tannin 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 evidenoe of the uncertainty of 
chemical deductions. — H. and 0. Mail, Nov. 6th. 
■ ♦ 
CAN WE MAKE IT RAIN. 
The October number of the North American 
Review contains two articles under the somewhat 
startling heading “ Can we make it rain ? " The 
first is by General Robert G. Dyrenfortb, who has 
been attempting, and, as he believes, snoeessfally 
attempting, to produoa rain in distriots afilioted 
with drought, by moans of dynamite and other 
explosives. In the second article, Professor Simon 
Newcomb, the eminent astronomer, tries to drown 
General Dyrenfortb’s arguments and conolusions in 
a cold shower of sarcasm. It has been frequently 
noticed that heavy oannon.firing has been followed 
by rain. In lb70 an Amerioan author, Mr. Edward 
Powers, published a book entitled *' War and the 
Weather,” in whioh it is stated that 198 battles 
of the Civil War, including every battle of im- 
portance, were immediately followed by drownpours. 
Rosults suoh as these, however, need very careful 
criticism before any definite oondusion can be 
drawn from them, and it ooourred to several dis- 
tinguished men in the United States that the 
question was one of aufficient importance to deserve 
experimental investigation. A soheme promoted in 
1874 by General Garfield, General William Sherman, 
and others fell turough owing to lack of funds, But 
in 1890 the Hon. C. B. Farwell sueoeodod in ob- 
taining from the Department of Agriculture and 
the Amerioan Government a sum of 9,000 dole, 
for a new projeot, wbiob 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 Dyrenfortb was asked to 
take charge of the investigations, and he has now 
published the details of the first experiments made 
under bis direction. 
“On the .^th day of August," says General 
Dyrenfortb, " our party arrived at Midland, Texas, 
a email station on the Texas and Pacific Railway, 
situated on the Llano Estaoado, or Staked Plains, 
in a region whioh had been suffering from a 
severe drought of several months’ duration, and a 
Inok of good rains for several years. The party 
made ite headquarters at a point twenty-five miles 
from Midland, in the midst of a dry prairie beat- 
ing little vegetation but soattered olumiis of grass 
and low mesquite bushes, with here and there a 
cactus. The plan of oporations 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 oonsist of a large number of ground batteries, 
where heavy charges of dynamite and raok-a-roek 
powder would be fired at freijaeot intervals. The 
next line to the rear was to oonsist of a number 
of kites flown to a oonsiderable height by electric 
wires, bearing dynamite cartridges suspended from 
them, to be fired high in the air. The third and 
main line was to consist of explosive balloons, 
• So that the proportion of tannin in tea containing 
3'2l per cent of theine would be about 12 per oent ? 
— Ep. T, .4. 
