184 EXPERIMENT STATION. [Jan. 



the water in the soil becomes charged to a certain extent with 

 gas. In the course of time, where the leakage is more or 

 less extensive, the odor of the soil becomes extremely obnox- 

 ious. This odor disappears very quickly when the soil is 

 aerated; in fact, when a gas leak is found it is an excellent 

 idea to leave the ditch open for a few days, to get rid of the 

 strong odors which are present in the soil. There is a certain 

 capacity of adaptation of plants to poisons, and this probably 

 exists to some extent in the case of trees ; but this capacity is 

 limited, and where the leakage of gas is continuous, the 

 roots are sure to be poisoned in time. The writer has treated 

 various small trees and plants with gas, and has grown plants 

 in water charged with it. Gas, like many other poisons, acts 

 as a stimulus to plants at first, but eventually kills them. It is 

 possible, however, to keep roots alive in water charged with 

 gas every twenty-four hours for a considerable length of time. 

 Finally, however, after the jjlant has absorbed a certain 

 amount the cambium layer is aifected, and disintegration^ 

 takes place rapidly. It requires a considerable amount of gas 

 to kill a large tree, but it must be borne in mind that the 

 conditions surrounding a tree are favorable for maintaining 

 gas in the soil for a long time. Mr. H. A. Ballou, one of 

 our former students, treated a large maple tree with 1,000 

 cubic feet of gas. This was done by digging a hole in the 

 ground under the feeding roots to a depth of four feet or 

 more, and the gas was allowed to escape into the soil at this 

 point for a number of months. The result was that not the 

 slightest injury was done to the tree. If, however, the same 

 amount of gas had been allowed to escape near a tree located 

 on a macadamized road, and the leakage had extended over a 

 period of two years instead of three or four months, some 

 injury would have been discernible. 



Many gas companies now openly recognize the fact that a 

 certain amount of gas leakage occurs continually, and that a 

 certain number of trees are likely to be killed each year; 

 therefore, they endeavor to settle all claims for damages to 

 trees arising from gas out of the courts. In Massachusetts 

 the court has decided in more than one instance that a good- 

 sized, well-developed and sound tree in front of an estate 



