GENERAL CONSIDERATTON OF PLANT DISEASES 29T 



The fumes are apt to destroy any vegetation within a radius of 

 several miles of the southern copper smelters. They are also working 

 destruction in the forests of Montana, California and other states. The 

 action of the fumes is peculiar and variable. Some trees succumb 

 quickly to their deadly effects, notably white pine. Other trees are 

 more resistant, including spruce, it is said. Nor does the gas act uni- 

 formly. Its effects vary with topographic conditions. The fumes 

 will travel long distances up a canyon or narrow valley, destroying the 

 woo'ds in it, but leaving trees uninjured on either side. Again, it is 

 said, the sulphur fumes collect in globular form something like soap 

 bubbles, and drift away, doing no damage until the globular mass dis- 

 perses, sometimes at quite a distance. To a greater or less extent, 

 forests at a distance of several miles from copper smelters may be 

 damaged by the fumes. 



It is admitted that the fumes can be controlled by condensation or 

 consumption, but the commercial practicability of the process is the 

 pending question. The fumes can be and are to a certain extent con- 

 verted into sulphuric acid, but the smelter people claim that the market 

 for this product is limited, and that it does not pay to produce more than 

 a certain quantity of it, as an oversupply sends the price down, which 

 would make it not worth while to control the fumes further. 



Just now considerable trouble is being experienced in Tennessee 

 and Georgia on account of the sulphur fumes from copper plants. 

 In 1905 the State of Georgia took action against these companies, 

 alleging that they permitted a discharge of gases, which destroyed 

 vegetation, including forest trees, in that state. The companies were 

 forced to install plants to utilize a considerable percentage of the sul- 

 phuric acid gas. These plants, however, have been unable to utilize 

 a sufficient quantity of the gas, and last spring the supreme court de- 

 cided to have a special expert ascertain the amount of gas released, 

 and the amount which ought to be utilized in order to make the 

 fumes harmless. 



The time is close when the pathologist will have to take up this 

 question of fume damage, since large sections of the Cherokee area are 

 subject to such damage, and it is reported that the injury has extended 

 to the Georgia area. 



The injurious effect of illuminating gas and ethylene upon flowering 

 carnations has been investigated by Crocker and Knight.^ The best 



1 Crockf.r and Knight: Botanical Gazette, 46: 256-276, 1906. 



