14 



INJURY TO VEGETATION BY SMELTER FUMES. 



TABLE 2. Analyses of injured and uninjured needles, etc. Continned. 



COMPARISON OF YOUNG AND OLD NEEDLES ON PINES NOS. 2 AND 3. 



a "This year's needles " refers to the young needles grown in the same year as that in which 

 the experiment was made; "needles of previous years" are those which remain over from the 

 growth of previous years. 



ANALYSES MADE IN THE BUREAU OF CHEMISTRY. 



A chemical examination of the needles from the pines and leaves 

 from the cowpeas used in the author's experiments gave the following 

 results : 



TABLE 3. Effect on pine trees and cowpeas of fumigating with varying strengths 

 of sulphur dioxid, as shown by the sulphur trioxid determined in the foliage. 



It will at once be seen from the three tables given above that all 

 plants treated with sulphur dioxid contain more sulphur trioxid in 

 their leaves than plants not so treated, and that the percentage of 

 sulphur trioxid in the ash of fumigated trees is higher than it is in 

 trees that have not been fumigated. Consequently, a method is at 

 once suggested for determining whether the trees around the plant 

 of the Mountain Copper Company have been killed by the fumes or 

 have died from some other cause. 



SULPHUR TRIOXID CONTENT OF THE FOLIAGE OF TREES SURROUND- 

 ING SMELTERS. 

 ANALYSES OP FOLIAGE ABOUT THE COPPER SMELTER NEAR REDDING, CAL. 



Having now shown that trees are killed by minute quantities of 

 sulphur dioxid and that usually this injury is accompanied b}' an 

 increased content of sulphur trioxid in the leaves and ash, the next 

 step is to see whether the dead trees around the Mountain Copper 

 Company's works usually contain more sulphur trioxid than those 

 trees which stand close by, and therefore have the same soil, but have 

 not been killed. The results of these determinations are contained 

 in Table 4. 



