84 
SUPPOSED EFFECTS OF THE GASES OF BRICK-KILNS. 
circumstances, when the orchards were in bloom, 
for the delicate blossoms to be injured even at the 
distance of 12 to 15 miles. I did not say the 
orchards would he killed , in either case. I have ar¬ 
rived at these conclusions after a close investigation 
of more than seven years, during which period I 
have frequently witnessed the injurious effects of 
these gases strildngly manifest at 'a great distance 
from brick-kilns, as well as in their vicinity; al¬ 
ways, of course, in the direction in which the 
wind was blowing at the time the gases were pass¬ 
ing from the kiln. 
During the past season the destruction of the 
fruit, the New Town Pippin especially, for many 
miles each side the Hudson River, between New 
York and Albany, has been very great. The season 
before the last the orchards generally escaped, 
owing to the prevalence of a drought for a great 
part of the spring and summer, though during a 
fog in June I lost the fruit on eight hundred New 
Town Pippin trees from the gas of a burning brick¬ 
kiln ; for it is admitted that without moisture the 
injury is slight, if any, at any considerable distance 
from the kiln. I am well aware, while ascribing 
the great destruction of apples, &c.,on the Hudson, 
to the gases of brick-kilns, that the little insect 
called the Aphis has also been very numerous, and 
proved destructive to the leaves of the trees, and 
consequently injurious to the fruit of many or¬ 
chards ; but any person who will take the pains to 
investigate the subject properly will find no diffi¬ 
culty in distinguishing the effects of the one from 
those of the other. When you examine the leaves 
on which the Aphis is making his banquet, you find 
him sucking the juices from the under surface; and 
the leaves appear thinner than those which remain 
uninjured. But where the injury is produced by 
the gases of brick-kilns, the leaf is destroyed on 
that part where the moisture would naturally settle ; 
that is, the pendent or lower edge of the leaf is 
dead, and often cut off for half an inch or more, 
and the part adjacent turned a dark color. If the 
leaf is so bent or formed as to collect the moisture 
on any other portion of it, you will then find this 
portion also killed and turned brown. The wounds 
produced upon the leaves by the gas are far more 
injurious to the fruit than any arising from insects; 
for even where a small portion is destroyed by the 
former it produces diseased action in the whole leaf, 
and by corrupting the juices injures or destroys the 
fruit; and would in time no doubt injure the trees 
also. 
I have no desire to represent the injury to fruits, 
vegetables, &c., from the gas of brick-kilns, any 
greater than it is, for I believe it is bad enough. 
My only object in bringing this subject before the 
community has been, that it may receive a thorough 
investigation ; that the truth or fallacy of my state¬ 
ments may be proved; that if true (of which I 
have not a doubt), an end may be put to the evil as 
soon as possible, by discovering some material 
which may be mixed with the clay, or the bricks 
before burning them, in order to prevent the forma¬ 
tion of gases destructive to vegetation. By burn¬ 
ing only late in the fall, and during the winter 
months, no injury would be produced. This plan 
will be adopted the coming season by at least one 
proprietor of a large brick-yard, who has been con¬ 
vinced of the propriety of this course by the injury 
which his own orchards and those of his neighbors 
have sustained during the past summer. I believe 
a sense of justice and propriety will induce others 
to follow his example when they have looked into 
the subject.(a) R. T. Underhill, M.D. 
New York and Croton Point, Jan. 1 9th, 1847. 
(a) The observations of Dr. Underhill may be 
corroborated to a considerable extent from several 
causes tried in Liverpool some time since, founded 
on proceedings by Sir John Gerard, of Lancashire, 
against certain alkali manufacturers for enormous 
injuries done to his woods. He claimed compensa¬ 
tion of the defendants for extensive damage alleged 
to have been done to his timber by the vapor pro¬ 
ceeding from the chimneys of the works, the effects 
of which were said to have been felt at a distance 
of one or two miles. 
Notwithstanding there was much conflicting tes¬ 
timony adduced by the parties on all sides, it was 
incontestably proved that injury of the most exten¬ 
sive kind was caused by the acrid gases of the 
alkali works. The plaintiff rested his claims upon 
the fact that the trees most exposed to the works 
were most injured; that they had been healthy 
until said alkali works were put in action; that 
the destruction of the trees consisted in their leaves 
being scorched or browned ; that they then became 
“ stag-headed,” and that there was no apparent 
cause for this sudden change from a state of vigor 
to one of rapid decay, except the presence of nox¬ 
ious acrid vapor in the air. That such vapor was 
discharged from the defendants’ chimneys into the 
plaintiff’s park and grounds, was proved by persons 
who had watched it; that it was of a very acrid 
nature, caused their eyes to smart, and produced 
coughing when it entered their lungs, although two 
miles off. That these symptoms indicate the pre¬ 
sence of muriatic acid gas; that muriatic acid gas 
is largely thrown off by the chimneys of alkali 
works, and that it produces noxious effects on 
plants similar to those which were observed in the 
plaintiff’s woods, was also conclusively estab¬ 
lished. 
It was a noted fact that the injury was chiefly 
done to oaks, ashes, and larches. Not that other 
trees escaped; on the contrary, limes, beech, Spa¬ 
nish chestnuts, and elms, furnished their quota, but 
to an inconsiderable amount. Hazel, it is said, 
escaped altogether, and alders, sycamores, and young 
Scotch firs suffered little, if at all. Old Scotch firs 
were, however, greatly damaged. This is no doubt 
connected with the powers which different trees 
possess of resisting external poisons. The oak, 
larch, and ash, are the most tender leaved of forest- 
trees when the leaves are young, and it might be 
expected that they should be most easily injured by 
muriatic acid gas. The sycamore, on the contrary, 
is naturally able to resist the sea-spray, which has' 
an analogous action to that of muriatic acid gas; 
hazels and beech are guarded by their copious hairs; 
alders by their glutinous varnish. Besides which, 
plants certainly have, like animals, specific powers 
of resisting poisons; and therefore it does not fol¬ 
low that because A and C are killed by x, that 
B, D and E shall also die. A dog is not killed by 
dropping hydrocyanic acid, perhaps the most subtle 
