THE TROPJCAt AGRICULTURIST. tSBPaEMBER i, 1891. 
THE APPROACHING REVOLUTION IN 
TEA FIRING. 
A Temperature Ixiicommended Lowtn ey Neael^ 
100° THAN THAT GfNBEALLY EMPLOYED ! 
We have had a visit from Mr. Davidson of 
" Sirocco " fame, — the patentee and manufacturer 
of many hundreds of updraught and downdraught tea 
driers, which are so largely in use in India and 
Ceylon. Mr. Davidson has been connected v/ith 
tea, as planter, buyer and sellor, and, latterly, 
in the useful and important capacity of machinist 
Bicce 1864. He knows as much about the culture 
and manufacture of tea as any man living, per- 
haps ; but like all truly scientific men he has not 
only not been ashamed of ever learning, but has 
had the courage fairly and fully to face and 
unlearn what seemed fixed principles in the 
pursuit. Until recently Mr. Davidoon firmly 
believed in and taught the doctrine ttiat a 
temperature of 240 degrees was the best in tea 
drying. A series of most interesting experiments 
in the laboratory and with bis downdraught driers 
has convinced him that he has been mistaken ; and 
while on estates in India he has doubled the average 
value of teas by preparing them on the new 
prinaiple of drying at so low a temperature aa 
130". This, he explains, means a temperature of 
150° in the heat cf ihe sirocco, the evaporation 
of moisture from the lea? keeping it down to 130°. 
Before getting so dry as to rise above that tem- 
perature, Mr. Davidson advises that the tea 
shou.d, near the close of the drying process, 
bo removed to and finished cff in a separate 
sirocco, the heat of which should be only 13^°. 
To our question whether this would not greatly 
extend the tirriS required to dry quantities of tea, he 
Y' plied that tuch an obj'^etion was obviated by power 
applied to the dovsndiaught which would cause the 
air to pass through the tea at the rate of eighty 
miles an hour. The philosophy cf the reformed 
process Mn. Davidson explains (0 be the preserta- 
tion by the use of the reduced temperature of the 
. volatile oil, on which, more than any other con- 
stituent, the fine flavour of tea depends. At tho 
high ttLcperatures of 240 deg, and even more 
formerly used, this oil was dissipated, and what 
Mr. Davidson deems the very poor substitute 
which is technically called " maltiness " took its 
place, We quite understood Mr. Davidson to add 
that the carrying on of the curing process at a low 
temperature would also put an end to the 
persistently repeated complaints of the non-keep- 
ing qualities of Ceylon tea. He ascertained in 
the oourfe of his iuvebtigations that the better 
keeping qualities of the weaker China teas is 
due to the really low temperature at which they 
are fired. — All this is not only exceedingly in- 
teresting but very important, and it is a 
fortunate coincidence that Mr, Djvidson should 
land at Colombo during the festivities which will 
draw so many leading planters to Colombo. To 
these Mr. Davidson can fully explain and with 
them he can discuss the principles on which the 
new process, which really amounts to a revolution 
in tea drying, are founded, with the various de- 
tails of power, exhauat fans, &o. After a short 
time in Colombo (when appoinments to meet him 
can be made through Messrs. Maokwood & Co,) Mr. 
Davidson, to whom Ceylon is new (he having only 
touched at Gallo a score of years ago), means to take 
a tour through the tea estates, tlio reswlta of 
which may be profitable to him in giving him 
adaitional information and leading to new con- 
nections, end fresh improvement in Lis machi- 
nery, while the information which bo as scien- 
tist and machinist has to impait cannoi but 
be advantageous to the planters and to their fast 
advancing enterprise, which, at this crisis in its 
history, needs all the help that experience, 
Bcientifio research and improved appliances can 
afford. We have had abundant proof that we 
have greatly underrated the producing powers of 
our soil and climate ; and while quantity is so 
rapidly increasing, it is of the utmost importance 
that quality should be kept up to the highest 
possible point. This is what Mr. Davideon is 
confident can be done by the adoption of the new 
method of drying the leaf, of which we have given the 
main principles, and which Mr. Davidson is ready 
and willing to explain in full detail. 
In justice to Mr. Jackson we feel bound to 
recall the fact that he also has been addressing 
himself to the solution of the problem of drying 
tea at a lower temperature than has been usual. 
In the de£OriptioD of his new machine, the 
"Britannia," it is stated: — 
At the present time, approximately two-thirds of 
the tea exported from Ceylon and India is being 
dried at a temperature of from 240 to 800 degrees. 
This high temperature is resorted to, simply to get 
the work out of the machines, the retult being that 
brokers and dealers, have from time to lime, and 
are at the present moment, comme ntiog on teas being 
high-fired, scorched, and that they will not keep. In 
designing and experimenting with the Britannia 
Dryers, which has occupied Mr. Jackson's time for nearly 
two years, he has steadily kept in view the necessity 
of improving the tes, especially its keepiog qualities, that 
the temperature at which the Britannia Dryers should 
work, must not be higher than the tea will bear 
even it left in the machine for an undue time, and 
Planters will at once realize the great importance 
of this. It will also be patent to all, that working 
at the reduced temperature is eaey and prtcli- 
cally obviates destruction of the air beating stove, 
which is built on an improved and durable principle, 
and should require no repairs for many years. 
Most Planters will be able to appreciate the 
principle under which Tea Rollers work, i.e. a 
charge of leaf is put in the machine, pressure is 
applied, and the machine is left to do the rest. I'lie 
Britonnia Dryers practically do the same ;— The 
leaf is fed into the trays forming the endless web, 
fuel is put in the furnace, and the machines do 
the rest. This at once removes ail tedious attention 
reuqired in Dryers using trays, and other drying 
surfaces requiring manipulation by hand, and all 
conversant with mechanism must know that automatic 
machines of all kinds are the best. The trays forming 
tbe endless web in the Britannia, are individually 
pivoted on the chains ; they follow each other closely 
hut do not come in contact wiih each other, or ■wLtb 
auy part of tbe machine whatever, consequently there 
can be no wear and tear on them. The Britannia Dryers 
have the nice arrangement, tbat the endless web comes 
continuously out of the drying chamber, which not only 
permits constant examination, but allowing the web to 
c^ol down,, obviates any risk of soiching the tea by 
contact. 
The fan of the Dryer is a very powerful one, is per- 
fectly balanced, and so strongly built, tbat it is capable 
of having as much higher velocity imparted to it without 
danger. The bearings are on the self-adjusting prin- 
ciple, and a novel acd neat arrangement prevents waste 
oil escaping at the ends of the bearing. Tbe saving in 
first cost of one of these machines, in labour to work 
it, in space occupied, in fuel, &c., is great when com- 
pared with a number of small machines, but this is a 
secondary matter when compared with the far more 
important consideration of obtaining nice flavoredi good 
keeping uniformly dried Tea, 
