CHEMICAL DATA. 



17 



circumstances. The air currents or the contour of the land might 

 be such as to cause one tree to get more sulphur dioxid than the 

 other, or one tree might be less vigorous and therefore more suscepti- 

 ble to the action of the sulphur dioxid than the other. For example, 

 two men, one strong and the other weak, might be working side by 

 side in some factory where they were both exposed to the same arsenic 

 fumes. It is perfectly possible that the strong man might breathe 

 the arsenic fumes day after day and not be affected, because of his 

 superior excreting power, etc., while the weak man might die from 

 the arsenic collected in his system on account of his inability to throw 

 it off. If the bodies of both men could be examined more arsenic 

 would undoubtedly be found in that of the dead man. The same 

 conditions could easily exist in the case of trees. 



ANALYSES OF FOLIAGE ABOUT A ZINC SMELTER AT LETMATHE. GERMANY. 



In Haselhoff and Lindau's work on the Injury to Vegetation by 

 Smoke and Fumes a large number of investigations upon this subject 

 that have been made in Germany are collected. One of these on the 

 injury to vegetation caused by the fumes of a zinc smelter at Let- 

 mathe is such an excellent example that a few of the tables will be 

 given. In Table 5 are given the results obtained by making analyses 

 of the leaves of trees situated in a westerly and southerly direction 

 from the smelter, all expressed on a dry sand-free basis. Instead of 

 selecting the trees in groups where some are injured and some not, 

 the injured trees are in this table taken from near the smelter, and 

 the uninjured ones from a greater distance but in the same direction. 



TABLE 5. Sulphur trioxid content of foliage from trees about a zinc smelter at 



Letmathe, Germany. 



