January 13,1881. ] JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 21 
13tli 
Th 
Royal Society at 4.30 p.M. Sale of Orchids at Mr. Stevens’ 
14 th 
F 
Quekett Microscopical Club, 8 P.M. [Covent Garden. 
15th 
s 
16th 
SUN 
2nd Sunday after Epipiiany. 
17 th 
M 
Royal Geographical Society, 8.30 P.M. 
18th 
Tu 
19th 
W 
Meteorological Society, 7 P.M. Society of Arts, 8 p.M. 
GALVANISED WIRE AND FRUIT TREES. 
(Concluded from page 2 .) 
UBLISHED evidence on this subject has 
, shown that the injury to trees is by far the 
most pronounced where smoke prevails ; and 
if the cause of that injury is due to the escape 
of acid from the wire then it seems to follow', 
as was stated last week, that all the worst wire 
—that containing the most acid—has happened to 
be sen ^ ^ ie y i c i n ^y °£ towns, and the best— 
that containing the least acid, to the country districts 
where the air is pure and the trees not nearly so 
seriously nor generally affected. It is not possible that such a 
division of injurious and safe wire could have occurred by 
chance ; and the different effects of the wire, assuming that the 
escaping acid is the sole cause of the injury, can only be ac¬ 
counted for in one way—namely, that the wire has a much 
slower sale in the country than the town, and often remains in 
stock for a considerable time in the shops of local ironmongers 
until most or all the acid has escaped from it ; but in towns 
it does not remain in stock nearly so long, and is consequently 
newer and more noxious to vegetation. This contingency is 
worthy of mention, for it is certain that old wire is much 
safer than new. Although the “ escaping acid ” theory of a 
practical man does not, to my mind, settle the question at 
issue in a satisfactory manner, it must not be altogether 
ignored, and it will be decidedly safei’_to use old wire than 
new, and especially that which does not bend freely, as its 
brittleness is evidence of its long immersion in the acid bath. 
I pass now to another aspect of the case, and one that 
demands careful attention. Whatever injury may result from 
acid within thejwire. I think it can be demonstrated that the 
branches of trees secured to zinc-coated wire are injured by 
the action [of acid from without acting on the zinc surface 
with which the shoots are brought in contact. It is on this 
basis, and, so far as I can see, on this alone, that the different 
and conflicting statements that have been published can be 
reconciled, and this accord being effected we may hope to 
find an answer to the vexed questions—1, “ Why is the wire 
injurious in some cases and not in others ?” 2, “ Why is the 
injury to trees so slight, or non-existent, in the pure air of the 
country, and so serious in situations where the atmosphere is 
impregnated more or less with the sulphurous compounds of 
smoke and^vapours from ‘ works ' and manufactories ? ” If 
these questions are not already answered, the following fact, 
which I think is indisputable, will complete the reply—namely, 
that sulphuric acid combined with zinc forms white vitriol— 
sulphate of zinc—which is a corrosive poison, and I will 
further show that sulphate of zinc is the active agent of the 
injury under examination. 
After the publication of the various letters on the question 
at issue, it was considered most desirable that a subject of 
such practical importance should not be left in the uncertain 
state it was. Different kinds of wire were therefore obtained 
last spring, to which the young laterals of Vines were secured 
in a small house in a decidedly “ smoky district,” for it is 
within the sound of “ Big Ben ” of Westminster. The 
following were, briefly, the results :—1, New galvanised wire, 
serious injury. 2, One-year-old galvanised wire, slight injury. 
3, Two-year-old galvanised wire, scarcely any injury. 4, Char¬ 
coal-drawn wire, no injury. 5, Copper wire, no injury. 
6, Pure zinc wire, no real injury (but not put up soon enough). 
7, Painted galvanised wire, new or old, no injury. Where 
the growths touched the new galvanised wire corroded specks 
were apparent in four days, and in a month the injury was 
severe, and was equally apparent on the shoots, tendrils, foliage, 
and berries that were placed in contact with it. Eventually 
the wire became covered with a thin film of oxide ; as this 
increased the injurious power of the wire decreased, and 
towards the autumn the wire had little or no effect on the 
harder wood. Long before the autumn, however, and as soon 
as the effects of the different wire were apparent, the whole 
subject was considered, and I was supplied by Dr. Hogg with 
a packet each of oxide of zinc and sulphate of zinc with the 
object of proving the presumed safety of the former and 
danger of the latter. The results were exactly in accordance 
wuth the anticipations. On worsted being saturated with a 
solution of the former, tied round the stems and wires, old and 
new, and kept moist, no injury whatever followed ; but on 
whatever kind of wire the sulphate oE zinc was placed and the 
shoots attached to them, injury immediately followed, and this 
of a kind precisely similar to that communicated by the new 
galvanised wire. On examining laterals injured artificially 
with the sulphate of zinc with those affected naturally by the 
wire, no difference whatever could be detected between them ; 
in fact, it was utterly impossible for anyone to whom injured 
portions were submitted to determine which had been injured 
artificially and which had sustained damage by ordinary 
contact with the wire. Some shoots that were girdled with 
worsted saturated with the sulphate of zinc were speedily 
killed, others that rested on the poisonous solution were only 
corroded on one side, the same as those resting on the wire. 
I am confident that whoever adopts the plan recorded will 
experience the same results. 
We have here a few important facts in precise harmony 
with each other. Sulphuric acid combining with zinc produces 
sulphate of zinc—sulphate of zinc corrodes Vine shoots in 
contact with it; sulphuric acid is more abundant near cities 
and towns than in the country where there is little or no sul¬ 
phurous vapour—injury to trees in contact with galvanised 
wire follows where smoke prevails, but is much less marked, 
■when observed at all, where the air is quite pure; old wire 
covered with the protective and innocuous oxide is compara¬ 
tively safe ; new wire, especially near towns, is decidedly 
dangerous to vegetation that is in contact with it. These 
facts appear to point directly to the conclusion that the cause 
of the injury under notice is that above indicated, and, what is 
more, they do not seem to be so well reconcileable on any 
other basis that has yet been suggested. 
i 
No. 29.— Von. II., Third Series. 
No. 1685. —Yon. LXV., Old Series. 
