NATURAL SCIENCES OE PHILADELPHIA. 
121 
In reviewing these simple facts several questions naturally arise which, 
possess more than ordinary interest for the vegetable physiologist, and may 
lead one step towards eliciting new developments in the chemical organization 
of plants. 
Although no narrow nor definite limits can be drawn, still, the general char- 
acteristics tend to prove that a sympathy does often exist between genera of 
the same natural order. In glancing over the following memoranda of the 
effects of carburetted hydrogen gas upon each genus, this sympathy is fre- 
quently apparent throughout the various members of a family.* 
Without venturing on further comment or attempting more than a brief out- 
line, these facts are presented with the hope that the attention of chemists in 
their experiments upon vegetable organism may be directed towards further 
researches. It may be well enough to remark that the enumeration of the 
species under each genus was not deemed necessary. Wherever they were 
differently affected they have been so specified. 
The natural classification of Lindley's Vegetable Kingdom has been adopted 
in the arrangement which follows, and the remarks are as much condensed as 
practicable. 
In the Transactions of the Society for the encouragement of Industry in Prussia, (1857) 
is published an interesting extract from a report by Prof. Dr. E. L. Schubarth, of Berlin, to 
the Belgian government, " on the acid gases which escape from the manufactories of sul- 
phuric acid and of soda, and the means to render them innoxious." It seems that " numer- 
ous complaints of the farmers that the vapors from the chemical manufactories in Belgium 
injured the vegetation of the fields and gardens, induced the government (of Belgium,) 
to appoint a commission to examine this matter. This commission consisted of chemists, 
botanists and farmers. During the summer of 1855, the excitement among the people, 
who even ascribed the potato-rot to the influence of the chemical factories, had so much 
increased that several attacks were made upon the factories. The government, therefore, 
increased the number of the commissioners, and at the end of the year, they made a report 
which was published under the title " Fabriques de produits Rapport a M. le ministre de- 
i'lnterieure par la commission d'enquetre, Bruxelles, 1856." They say it was an admitted 
fact that vegetation is injured by the acid gases from chemical works, but this influence 
is often overrated ; the spots on the leaves, and injuries of the flowers ascribed to acid 
gases, are very frequently the result of other causes, as frost, microscopic, vegetable, and 
animal parasites, deposits of foreign matter upon the leaves, very intense sunlight, etc. 
The potato-rot is certainly neither caused nor increased by these gases. On the other 
hand, chemical investigations proved the presence of traces of hydrochloric acid in spotted 
leaves, and in the dew upon the plants. Similar spots could be artificially made by mois- 
tening the leaves with dilute hydrochloric acid, the presence of which could be proved 
after an interval of eight days. The report contains a list of trees injured by these gases ^ 
* Several chemists of high reputation have made examinations of the gas of the Phila- 
delphia Gas Works, but, from some cause, their results are at variance. In order to facili- 
tate the further researches of such as may desire to investigate its effects on vegetable 
organism, I insert the analysis of Dr. C, M. Wetherill, made in 1852, for the'engineer ot 
the Philadelphia Gas Works, This is probably as nearly correct as can at present be 
determined. 
Percentage by volume, gases dry, at 0° centigrade, and 1000 Millimetres Barometer. 
A. 
B. 1 
B. 2 
defiant gas and hydrocarbon vapors, 
8.157 
8.963 
9.023 
Oxygen, 
0.052 
0.136 
0.120 
Hydrogen, 
44.168 
41.620 
Carbonic oxide, 
5.081 
Nitrogen, 
0.059 
100.000 
Journal of franklin Institute, Philadelphia, July, 1854, Vof xxviii. No. 1. 3d series 
1848.] 9 
