November i, 1S90.] 
THP TROPICAL AGRICULTURIST, 
359 
begin to movet ill from tbrf e to six weeks, and it takes 
about six months to remove all tbe scale. Though slow, 
it appe'ors to be certain, and should be perserved with. 
In a communioation from the railway offioer indi- 
cated we find it stated that 
The leaves are at present purchased from the Horti- 
cultural Gardens, Lucknow, though at most two 
years hence we will have our own supply from young 
plants bought from the above gardens or raised in 
Gorakhpur from seed. 
The advertised patent fluid, called the extract of 
“Eucalyptus Globulus” is sold at R3-8 per gallon 
in Bombay. We got plants of the Eucalyptus globolus, 
rostrata aud resu.ifera. Tbe whole of the first died 
but tbe other two are g.vowiug vigorously, and I do 
not find that there is any more strength in the liquid 
from tbe globulus than from the others, so our sup- 
ply is certain. 
We extract 1,000 gallons of strong liquor from one 
mauud of leaves, which cost us in Gorakhpur 112-8 
with R5 for fuel, and cost of labour nil ; — total one aud 
a half pie per gallon. 
We put into a dirty boiler 12 gallons of liquor and 
repeat it after each tiip of from 300 to 450 miles. The 
action begins utter the first trip, aud takes the scales 
clean off the copper box in a monlh, and is during 
this time acting more slowly in softening and loosen- 
ing scale from the iron shell, aud s'.ill more slowly 
from the bra.ss tubes. 
From mv pres-nt knowledge of this fluid, I think 
it will 'ake no less tha i six months to remove all 
the obiicionaoe scale from a boiler at a cost of 
R5 a d R3 per hali-y"! r per hoi er aft- rwaids, 
Th sav ug lo coal sh u d be many iime- Un above, 
no , to men iuu the sav ng we , xpecfc in repai, ,s to boilers, 
as als ■ i i washioi >m. wat-r, as I find we can run 
from 1,000 to 1 2C0 miles without a wash-out, and witli- 
out priming. Our old system was to wash-out after every 
300 to 4 /0 miles, and then ofion have to b'ow off half a 
glass of w’atof on account of priming before the ruu 
was complete. 
Th-! scale comes of 1 oth softened and in large pieces, 
and in great quant ti, g, as jou have s“en. AVheu first 
it is pub into dirty boilers, g eat care is needed to see 
the wamr space- do nos became solid, as the seaio will 
block them if allowed to remain too long without a 
■wash-out. 
Altogether, the results so far are very satisfactory, 
and I will dully report the iutemal appearance of the 
first bfiler I have ooca ioii to examine as to whether 
pit ing ha.s ceased or not. 
The maund mentioned is, we presume, the maund 
of 80 lb., and from this quantity of leaves, it 
will be seen, no less than 1,000 gallons of strong 
liquor (strongly acidulous, we presume ?) can be 
obtained. This seems a most important use to 
which the gum tree leaves, rich in an essential 
oil, valuable lor many other purposes,— including 
the treatment of diphtheria, — can be put, and we 
cannot doubt that local exoeriinents after the 
Indian example will be instituted. The uses of 
the Australian trees are many and varied. For 
instanos tbe pitie-like foliage of the casuarinas is 
not only a good fodder for animals, but, as we have 
learned recently Ir an Madras, a substitute for 
mulberry leaves in the feeding of silkworms. 
Oct. 12ih, 
After a pretty strong blow of wind from the 
norlh-west last tvoning, there is a lull this morning ; 
and it looks as if we were to have aoother interval of 
line weather btforo th i north-east monsoon puts itself 
in evidence. The raiufallfor the 24 hours has been 30 
oouta, BO that in four days wo have had nearly 2 in- 
ohhees, actual quantity measured being 2 05 inches. 

Tlll'l SAF OF TREES. 
70, Mark Lime, London, E.O., Sept 2Cth, 1890. 
Gentlemen, -T send you a short review of an inter- 
sling new work which is attracting considerable 
olico in Ec'.eutilic circles. The author certainly seems 
fo have made out a strong case in favour of the Sap 
deseendit'g instead of rising — aud it follows that if the 
leaves perform such important functions in obtaining 
plant food, it can scarcely be wise or economical to 
prune heavily as is the custom now on certain Tea 
plantations in Ceylon, Yours faithfully; 
John Huohes. 
A keen observer aud ingpiiious experimentalist, has 
been writing a book on “ Sap ; D es it Raise from 
tbe Roots ? ” a question which ho proceeds to answer 
wiih a decided ncgativ'C. To those who merely “run 
aud read,” the whole question and auswi r may appear 
as a very slight matter indeed. lu rtaaty, however, 
the right answer to the question is of great uioment to 
us all. In the first place, a negative reply simply 
means the ruthh ss upsetting of all our preconceived 
ideas, the reversal of what has b-.en taught in schools 
for ages. 
It is true that, if we examine into the theory of 
plant growth as set down by l-otanicsl and biological 
authorities, we find that they disagree among each 
other to an astonishing degree. Tuey ail, however, 
join in dcc'aring that trees and plants derive sap 
from their rcot.s, aud breathe io gases by their leaves. 
How the sap rises, whether by capillary attraction, 
endo-mose, root-pres.‘uire, suction, or evaporation, ora 
combination of all (de^cibed by Frofes.sor Huxley 
as pulling, pushing, aud pumping), the greatest 
biologists, inciudin.g Her'-ert Spencer, Sachs, Huxley 
Darwin, and others, have by no means been able to 
decide or prove. They all, ueverH.ele.'..s eiidor-e tlie 
theory of rising .‘ap, and ag'-ea n o.'e.over tbar it ri-es 
in spring aud deoends in summer. No'Jiq if all this 
the ribiug is proved to bo wrong, we si, a 1 not only 
have to alter our school teaching, buf. largely modity 
our agricu tural practice. Clearly if the roots suck up 
the so 1 will quickly become exhausted and require eou, 
atant feeding, while the leafy part.s of the plants mus. 
be cut and pruned down. This is the present practice. 
And it is certainly worthy of remark that our be>t cul- 
tivated — according to the theories of the day — orchards 
and gardens are thjfethat suffer most readily from 
bligVit and disease gent rally. Our new botanical revolu- 
tionist, Mr. J. A, Reeves, with bis book on “ Sap,” tries 
to prove that we are altogether on the wrong road ; 
that sap does not ascend, but descends ; and that 
gas does not descend but asce iris in all trees aud 
other plants. To the unpr- j ulieed physicist and 
mechanician this thfory of Mr. Reeves seems by far 
the must credible aud intelligible. It !■-■, for one thing, 
strictly in accord with the proved and univer.sally 
acknowledged laws ot gravitation. IV? all know that 
wa'er naturally falls, and can only be made to rise 
under great pressure ; absorption and capillary at- 
traction can only raise it some thirty feet in wet 
wood, practically not at all in dry wood. On the 
other h 'lid, gases naturally rise, and to reverse the 
process great force, exceptionally applied, mus be 
brought into play. 
These facts broueht home must be a fearful stum- 
bliiig-'olock to Rrofismr Huxley, though, doubtless, 
less so to Mr. Herbert Spencer. But we are told off- 
band that sap descend' iu autumn and lises in spring. 
Seeing the inipotsibility ot geiting liquids ah-orbed 
upwards by dry wood, how can we account for the 
aheged phenomena of lising sap in the dry trees in 
spring? In this connection it is remarkable that trees 
cut clown early in the year before they are in leaf will 
often sprout out some months after they have been 
severed from tbs roots and stacked aw.iy. Another 
curious fact is that a tree which has been “ ringed ” 
near the ground dies at the root first while the upper 
p-rt fli urishes. N.-Lody has yet observed tlie risiug of 
sap. Mr. Reeves has actually witues.-c.i its descent. 
To do this our experin/enta ist tested bis theory by 
removiug a ring of bark fiom a growing tree. Soon the 
sap was seen to accumu'ate on the npper edge of the 
bark, whdo the lower remained dry ; the sap gradually 
' descended aud liavdoned iu the air. A brauch cut 
clo.se to the tree bleeds profusely in the upper ptirt. 
Testing theories is always the safest plan. W’e find 
r-ots the driest parts of plants, the leaves the wet- 
