THE TROPICAL AGRICULTURIST. 
[May i, 1B82. 
periments which " G. W." desiderates, are just those 
for which we should like to have the aid of the 
Cryptogamist. There is however, a very striking 
contradiction been the experience of Mr. Ward as 
given in his Report (page 523, " Tropical Agriculturist," 
vol. Li) and the statement of Mr. Storck (who was 
Assistant to the well-known Botanist Dr. Seeman,) 
which is corroborated, s»ys the editor of the Gard- 
eners' Chronicle, by independent reliable authority : — 
(this will be found on page 911 of the "Tropical 
Agriculturist " et seq). We give the two passages for 
purposes of compaiison : — 
Mr. Ward. 
Carbolic acid is very slowly 
volatile, and with difficulty 
soluble in water, and where 
drops of the acid touch a 
leaf, &c, destruction of the 
tissues ensues. Carbolic acid 
has, moreover, a powerful 
odour, and it appears to be 
assumed in the experiments 
that the odour is a measure 
of so much vapour passing 
off from the mixture to be 
dissolved in the water on the 
leaf. I do not find, however, 
that the destruction of Hemil- 
eia spores in the neighbour- 
hood of the mixture is com- 
mensurate with the alleged 
results. It is true that, where 
water is in contact with the 
powder, a solution is obtained 
sufficiently strong to kill ger- 
minal tubes, but the diffusion 
of this over the leaf is a very 
slow process. Under any cir- 
cumstances the results of ex- 
periments with carbolic acid 
powder are not as yet en- 
couraging, though I am of 
opinion that more might be 
done with some modification 
of it,* if it were not for the 
fact that the accumulated 
powder and solution are a source 
of danger at the roots. 
I will pass on to the des- 
cription of a few illustrative 
experiments before reporting 
further on the larger ones. 
A sturdy coffee plant, of 
which two leaves were dis- 
eased with "rust patches," 
was placed in a small war 
dian case, the whole of the 
inside of which was painted 
with a saturated solution of 
carbolic acid in water. In the 
overpowering atmosphere pro- 
duced the plant was tightly 
enclosed. -After 24 hours 1 
opened the case and removed 
the plant : the odour of 
bolic acid was so strong, that 
one could with difficulty hold 
the head in the enclosure. 
Nevertheless, spores taken 
from one of the patches ger- 
minated nominally in 24 hours. 
It is thus clear that in usin^ 
carbolic acid (as with other 
reagents) the germinal tubes 
will have to be attacked with 
■a solution of the acid 
* As, for instance, using the 
weak powder alone on the 
leaves, and the caustic lime 
separately as a top-dressing 
Id the soil. 
Mr. Storck. 
An acre of coffee land con- 
tains thirty-six centres of 
vaporisation formed by tin 
vessels to be mounted upon 
short sticks, and covered in 
a peculiar manner, to protect 
the contents from rain and 
rubbish, thereby preventing 
waste and undesirable dilution 
by rain of the fluid contents 
of the vessel. They consist 
of a mixture of carbolic acid 
and water in the proportion 
from 3 to 10 per cent, of 
Calvert's best No. 5 acid, at 
the option of the operatdr. 
Any strength not exceeding 
25 per cent, may be used, since 
nothing touches the plants or 
the soil, nor injures the ten- 
derest young leaf or flower- 
bud. * * Two Liberian trees 
I simply furnished with a 
small bottle each, partly filled 
with my mixture of only 3 
per cent., hung into the angle 
of the lowest branches. Both 
trees have now been per- 
fectly free of the fungus for 
some weeks, and not a single 
one of their close neighbours 
been infected. They 
prove to have been completely 
isolated by the treatment, not 
single spore living to reach 
and infect the others, al- 
though in some instances 
almost touching. With the 
nursery, covering about three- 
quarters of an acre, I pro- 
ceeded in the following 
manner: — Judging that with 
so small an area as the above 
I should be working at a dis- 
advantage through the gas 
escaping beyond the limits of 
the area and going to waste 
in every direction, I arranged 
my centres of vaporisation a 
little closer than would be 
necessary on a large field, and 
put them 8 yards apart each 
way. The receptacles of the 
fluid and their covers were 
represented by ordinary cups 
and saucers, pressing the cups 
slightly into the ground and 
mounting the inverted saucers 
upon three or four short 
sticks stuck closely round the 
rim of the cups, I left a 
clear space of about 1 inch 
in depth between the rim of 
the cup and the cover. They 
were then charged with a 
dilution of 3 per cent., and 
the effects noticeable after a 
jfew days were most startling. 
Another experiment throws 
light on this subject. A thin 
layer of the mixture of car- 
bolic acid powder and lime 
was sprinkled on the surface 
of the mould around two 
coffee plants, and at 
watered. The watering was 
continued at intervals for 
three weeks, when one of 
the plants had but one yel- 
low leaf left, and the leaves 
of the other were pale and 
drooping. The effects of even 
a dilute solution of carboli 
acid at the roots are disas- 
trous, though in the case of 
a large strong tree they may 
be to a certain extent marked 
by other changes. 
But observations on whole 
estates prove the same, and 
I have failed to discover the 
good effects said to have 
been produced on estates by 
the treatment. That the ger- 
minal tubes are killed where- 
ever a solution of carbolic 
acid comes in contact with 
them is true; but such a solu 
tion is not produced in the 
way described in the experi- 
ments on Peradeniya, Glen 
eagles, Pallakelle, &c. 
If carbolic acid powder 
could be used with safety 
it would be more efficacious 
without tha lime, which could 
be used with benefit as 
manure ; but in face of the 
fact that whatever external 
application were used, it would 
have to be repeated at least 
every three weeks or so, it 
would be highly injurious to 
permit such an increase 
carbolic acid in the soil 
would be the case here. 
Mr- Storck. (Continued.) 
mend a density of 10 per 
cent. The effects of the first 
week's dense vapour will 
amply repay the extra out- 
lay in striking a deathblow, 
not only against the rust in 
full development but — which 
is the greatest triumph of 
my system — against the my 
celium of the fungus. This 
first blow will under these 
circumstances save a large 
proportion of the foliage, un 
less too far gone, by instantly 
arresting the development of 
the fungus, and killing all 
that may be still alive on the 
dead and dying leaves strew- 
ing the ground. If the dis- 
ease is not visibly present, 
all the better; the carbolic 
vapour will in a short time 
force it to show itself, chiefly 
in the character of dying 
mycelia, and save still more 
or all of the foliage which 
would have' gone in the next 
attack of disease. *** Choose 
your trial patch right in the 
centre of a good 100-acre 
field, and the experiment, 
conducted with ordinary in- 
The ripe spores with which 
the plants, then some nine 
months old, were fairly reck- 
ing, began to change colour 
from the wellknown bright 
orange to a dull ochre, until 
they subsequently turned into 
dirty yellow and then greyish 
white. They all, instead of 
as usual dispersing, remained ' 
in a manner glued to the 
leaves, and afterwards drop- 
ped with them, dead, harm- 
less, incapable of propagation. 
As time went on, all rust 
which came out began to look 
dull in colour and sickly, quite 
different from a healthy crop 
of spores. By degrees pale 
rings round the rust patches 
began to show, indicating the 
circumference of the mycelia 
and where their farther 
development had been arres- 
ted. In the third month a 
large proportion of the spots 
appeared pale green, whitish 
round the edges, and as if 
drying up in the middle ; 
some pushed out a few sickly 
spores, but very frequently 
none at all. The spots turned 
into dry tissue, and most of 
those leaves, unless too se- 
verely attacked, remained on 
the trees. Thenceforth a little 
dirty-looking rust still con- 
tinued to appear, but the 
presence of the disease, up 
to its complete disappearance, 
was chiefly indicated by dead 
and dying mycelia. From 
'hat I have witnessed, bare 
contact with the vaporised 
atmosphere seems, if not imme- 
diately to kill the spores, to 
effectually incapacitate them 
from germination. From mov- 
ing round in the nursery, 
examining the effects of the 
treatment, as I frequently 
did, I would often go in 
among healthy trees, handle 
their leaves, pull suckers and 
the like, but not a single 
instance of further infection 
took place among those trees. 
Liberian and Arabian, which 
were healthy when the pro- 
> started. "With grown 
trees, having leaves of denser 
texture and more uniform 
age than nursery plants, 
hich are almost always grow- 
ing, the effects, although ap- 
parently slower at the begin- 
ning, are in the end still more 
pronounced. They lose a 
greater proportion of leaves 
at the start, but all disease 
upon them and in them is 
dead before the fall, at once 
neutralising a fruitful source 
of re-infection. In the case 
of fairly vigorous trees a new 
coat of clean foliage, never 
again to be soiled by the 
levastating parasite, will hava 
formed by the time the last 
spore has disappeared. 
* * You may go on charg- 
ing your vessels with a den- 
