120 
PROCEEDINGS OP THE ACADEMY OP 
put forth their leaves in the spring, and grew through the season with their 
usual vigor. 
As a general rule the hardwooded plants fared the worst. Succulents were 
the first to wither, and the first to recover. Large numbers of both hard and 
softwooded lost their tender twigs and young wood, which withered and re- 
quired pruning as far back as the sound growth. While some showed signs 
of life, and began to put forth leaves within a few weeks, others lingered for 
months ; some died after a sickly existence, and many were killed outright. 
Some plants near the leak, and under the full influence of the gas, manifested 
no apparent injury ; others in the remote orchid house were violently afiected, 
exhibiting an astonishing sensibility. It seems rather anomalous, that of the 
Orchidacese, whose sustenance is derived mainly from the atmosphere, every 
individual should have exhibited a total indiflerence to the gaseous influence. 
Several large specimens of Bletia Tankervillicea, as well as plants of Cypripedium 
venustum, and insigne, passed unscathed through the heat of the battle. 
That plants in general are peculiarly sensitive to this gas, even when it is 
almost consumed by combustion, seems to be well established. The experience 
of florists who supply blooming plants at entertainments, is, that the plants 
having been thus exposed are often in a sickly condition for some time there- 
after. This is especially the case with Camellias. They frequently shed their 
foliage, and have been known to die after an exposure of a few hours in rooms 
where many gas lights were burning. This has no doubt been caused in part 
by the heated and impure air arising from crowded assemblages, but, if so, 
similar effects would be alike apparent in Horticultural exhibitions when open 
only by daylight. 
No experiment similar to that which we are about to record has ever, to 
our knowledge, taken place upon so great a scale, or included within its range 
so large a number of genera. Solitary instances have been occasionally noted 
in which a limited number of species have been brought within the influence 
of acid and inflammable gases. Examples are not wanting, indeed, to confirm 
the destructive effects of carburetted hydrogen on vegetable organism. Many 
of the fine old elms in the streets of New Haven have been killed by leaks from 
the neighboring main gas pipes. Similar effects have been observed in Boston, 
Albany, and other cities in the United States. 
In a review of a paper entitled " Ueber Gasfabrikation und Gasheleuchtwig 
com sanitdtspolizeilichen StandpunJcte ; von Dr. Innhauser. ( Wien. Wochenhl. 35, 
1856,)" the author quotes the observation of M. Ulex, of Hamburg, as follows : 
In this city there are a great many linden and elm trees. In 1851, one hun- 
dred and fifty-nine of these trees had to be cut down because they had died. 
It was found that the bark immediately above the ground, often as far up as 
eight to ten feet, was quite loose, and completely separated from the wood ; the 
roots soft and red, the fibres of the roots soft and rotten. The interior of the 
trees were perfectly sound. This injurious effect upon the trees is not only 
caused by the gas which escapes unburnt in the flame, but more particularly 
by that gas which leaks through the pipes in the ground. It was sometimes 
perceived at a distance of fifteen to twenty-five paces from the pipes. The 
same observations were made in Paris, Bordeaux, Diisseldorf, Mannheim, 
Basle, and Vienna. Professor Bertulus, of Marseilles, thinks that the com- 
binations of sulphur and ammonia in the gas saturated the ground with hydro- 
sulphate of ammonium, which also causes the black color of the soil."* (See 
Schmidt's Jahrbucher der gesammten Medicine. Band. 96, 1857. No. II.) 
* Although not strictly within the range of the subject at present under consideration, 
it may not be out of place to remark that many instances are on record which show that 
vegetation has been seriously injured by acid gases from manufactories, especially in 
Belgium and Prussia. The same causes are said to have produced similar effects in a 
modified form in the vicinity of Philadelphia. This may account for the unusual mor- 
tality among the Liriodendron ttdipifera, and other indigenous forest trees, killed front 
8ime to time in Fenn Square, in the neighborhood of the United States Mint. 
[May, 
