THE TROPICAL AGRICULTURIST 
[April i, 1892, 
738 
It h>B been foand, u a retail of elaborate experimenta 
that the beating power of an; fael, whother coal, ooke, 
charcoal, wood, peat, or turf, is approximately propor- 
tionate to the peroeutage, by weight, of I ho carbon 
which it contaiut ; hence, ooke, ooneiatiug as it does, 
almost entirely of oarbou, in a greater or leaser degree 
of parity takes the lead as a hoat-produoer. Anthra- 
oito a good eamplo of which coutaius 90 per omt or 
more of carbon, heads the list of coals. Its hardness 
and oompactnesB, and the absence of flame-produoing 
oonstitueuts render a strong draught and careful 
stoking easeiitial for its economical combastion. Other 
hard Welsh or steam coals have from 75 to 90 per cent, 
the average being about 84 per cent ; Newcastle coala 
avernge 82 per coot ; Derbyshire, 80 per cent : Scotch, 
78.5 per cent ; aud Lancashire, 78 per ceut. Of course 
extreme variations, upwards aud downwards, are fouud 
in all the above diatricts. Again, the “ heat-vaiuo " of 
any fuoi is modilied by tho preaeoce of (1) water, aa 
such, or of (2) the uucombiued hydrogen aud oxygen in 
the proportion in which they unite to form water, i.e., 
eight parts by weight of oxygen to one part of hydrogen. 
The greater the amount of water, or of its consti- 
tuent gasses, the smaller becomes the heating power of 
the fuel. 
The reasons for this are not far to seek. The heat 
disengaged in combination (uaing tbe word iu its ordi- 
nary sense), depauds upon tbe chemical oombination of 
tbe elements oentained iu tbe snbatance burnt with tlie 
oxygen of the air — the oarbou with oxygon forming 
oarbuuio acid gas, tbe hydrogen with oxygen formiug 
water. It is clear, then, that any elements exist- 
ing in a fuel already in a state of combination, are, 
from a heat-producing point of view, so much waste 
material. 
With regard to the presenoe of the hydrogen in an 
unoombined slate the case is somewhat different. Here 
the hydrogen oomhines with oxygen (present in the fuel 
itself, or iu the air), tbe nnioii being attended by the 
generation of a very large amount of heat, far greater 
than would be the result of the combustion of an equal 
weight of carbon. How then oan the hydrogen be con- 
sidered disadvautageoua to a fuel? Simply because a 
more than compeusatiug amount of heat is used up iu 
raisiog tbe temperature of the water to the boiling- 
point, and in ita conversion into steam. This will 
readily be understood, when it is remembered that as 
much beat is required to raise a pouud of water from 
freezing-point to boiling-point as would raise a pound 
of iron to about 900° centigrade (a bright red 
beat), and that five aud a half times as mneh 
beat would bo needed to turn a pound of water at 
boiling-point into a pound of steam at tbe same tempe- 
rature. 
These deduotiooa from theory ato fully borne out by 
the results of practical experiments, it being found 
that tho heating power of a fuel varies directly aa the 
amount of oarbou, and indirectly as tbe quantity of 
water and ita elements, or incombustible ash, con- 
tained. v i. i 
Hero wo are met by an apparent paradox, whion has 
led to much misoonoeptioc, and consequent error in 
praotioe, and which is therefore deserving of the atten- 
tion of practical men. 
It was first shown by Bunsen, that when steam is 
passed over red-hot carbon, it is decomposed ; the 
glowing carbon uniting with the oxygen to form carbon 
monoxide and carbon dioxide, and the hydrogen passing 
oS partly uncombined. The carbon monoxide and the 
hydrogen unite with oxygen (forming water and carbonio 
anhydride respectively), and the amount of beat thus 
generated is found to be greater than would ba evolved 
in tbe ordiunry oombnation of the carbon without tbe 
intervention of tbe steam. This application of water- 
vsponr must, however, bo carried out with great care, 
for when present in excess, it decreases, rather than 
augments, the beat generated. Tlio proper way to 
apply water for raising tbe temperature ie to place it 
in an open pan beneath tho firegrate, thus ntiliaiog the 
heat which is radiated downwards from tho fire for its 
vaporisation. Many have fallen into the error of wet- 
ting coal before placing on the fire, with the result that 
tho amount of bust has been lessened rather than in- 
creased, as is eyideat from wMwaa Mid aboye. IHs 
posaible that ooke, if fresh, may be advantageously 
damped in moderation, but it has the power of absorb- 
ing a large amonnt of moisture from the atmosphere 
without any aprinkliug. 
Too mucli emphasis cannot be laid upon tho uecce- 
sity for carelul and intelligent stoking, no matter what 
tbe class of fuel employed. Careful trial should bs 
made of various kinds used by any particular furnace, 
aud the stocking should be curried out iu each a man- 
ner as to ensure perfect and complete oombustiou. If 
anthracite or other hard ooal be used, for instanoe, thin 
fires and a strong draught are essential. Tbe impor- 
tauce o( atokiug was well seen in a case that came 
under the notice of the writer during tbe hard frosts 
of last winter. The furoacea of a market-nursery were 
stoked for soma time by a gardener whose only idea 
seemed to be to pile on tbe coal. A man who hud tad 
some years experience, an eegine-driver in a factory, 
was then pat on stoking duty, with tbe result that, in 
much colder weather, the coal consumption was reduced 
considerably. 
In oouoluaiou, tho main question as to which is tho 
most economical fuel for glass-bonses, is one that 
can only be determined by actual experiment with 
each system of heating, and by considering, inde* 
peudeutly and in conjunction, the Iieat-vaiue of 
tbe available fuels, the cost of each, and the kind of 
boiler used. 
The following table, taken from Sebeorer’a Metal- 
luryie, may bo useful, as indicating tbe relative heating 
effects of differeut fuels, although the figures must be 
taken with caution, as being the result of theoretical 
deduotious rather than that of practical experimenta 
with ordinary boilers. 
Fuel. 
Bower. 
Hood ooke, with 10 per cent moisture 
and 5 per cent ash . , , . 2,350 
Best ooke, 5 per ceut moistuio aud 3 
per cent ash , . . . . . 2,400 
Best coke, no moisture, aud 8 per 
cent ash . . , , , , 2,450 
Air-dried black wood charcoal, 12 per 
ceut moisture.. .. .. 2,450 
Anthracite, 5 per ceut moisture, 5 
per ceut ash . . . . . . 2,350 
Caking coal, 5 per cent moikture, 6 
per cent ash , . . . . . 2,300 
Sinter coat, 6 per cent moistnre, 5 
per cent ash . , . . , , 2,250 
Lignite, various . . . .from l,800to 2,200 
Turl peat (without moistnre) 2,000 
Turf peat, 30 per cent moisture . , 1,575 
Air-dried wood, with 20 per cent 
moisture . . . . . . 1,575 
Kilu-dried wood, with 10 per cent 
moisture .. .. 1,676 
Kiln-dried wood, without moisture . , 1,760 
C. W. H. G. 
—Gardeners' Chronicle, January 30tli. 
THE YATADBRIA TEA CO. OF 
CEYLON, LD. 
Tho annual meeting of this Company was held 
at 13 Queen Street, Oolombo, on the 26lh Feby. 
Mr. H. V. MasEFiau) was in the ohair, and the 
following shareholders were present : — Messrs. J. 
H. Starey (Managing Director), 0. M. Gwathin, 
J. R. Fairweather, B. G. L. Bremner (Secretary), 
and by attorney, Mr, W. W. Church and Mr. D. Fair- 
weather. 
The SECBETXBy read the notioa convening tbe 
meeting. Tho minutes of tbe extraordinary 
meeting held on 31st July 1891 were duly oonfirmed. 
The report of tbe direotors wbioh has Mready been 
pnblished which was taken as read, was as follows: — 
The Directors have tbe pleasure to submit the 
balance-sheet and profit and loss account for the year 
ending Blat Deoombor, 1891, duly audited. 
Tho balance of profit (including Rl,751'18 brought 
forward from livst year, aRor WiRiug off for doptoclA- 
