INJURY BY SMOKE, ACID FUMES, GAS, ETC. 39 



On the other hand transpiration is not affected by the 

 presence of the gas, neither is the absorption of water inter- 

 fered with. 



Notwithstanding the deleterious effects indicated, Wieler 

 does not consider them sufficient to account for the chronic 

 form of injury, and is led to believe that the true cause will 

 be found in the effect of the gas on the soil, and that such 

 continuous accumulation of sulphur dioxide in the soil is 

 responsible for all the injury due to smoke, the ultimate 

 effect resembling death due to drought. 



Haywood has investigated the action of smelter fumes. 

 The ore consisted of sulphides of iron and copper. Practic- 

 ally all the sulphur in the ore is burned and given off into 

 the air, principally as sulphur dioxide, but to some extent as 

 sulphur trioxide. For each pound of sulphur burned two 

 pounds of sulphur dioxide are formed and given off; this acts 

 directly on the foliage. Sooner or later all the sulphur 

 dioxide becomes sulphur trioxide, and in this form is found 

 in the leaves. Sulphur trioxide becomes sulphuric acid in 

 the presence of water, which also acts on the leaves. 

 Within a radius of three miles of the forge all vegetation 

 was killed, and even at a distance of nine or ten miles 

 numbers of fruit-trees, especially peaches, which are very 

 sensitive to injurious substances, were badly injured. 

 The author's conclusions are as follows : 

 Sulphur dioxide, when present in very small quantities in 

 the air, kills vegetation. 



Such injury shows itself by the increased sulphur trioxide 

 content of the foliage. 



Finally it is stated that in connection with this study it 

 might be of value to give some idea of the amount of sulphur 

 dioxide that is given off each day into the atmosphere by the 

 smelter. Analyses of three samples of the ore show that it 

 contains 4i'87, 40-06, and 42*44 per cent, of sulphur, or 41 -46 

 per cent, sulphur on the average. Since in extracting the 

 copper the sulphur is nearly all given off as sulphur dioxide, it 

 seems safe to assume that 90 per cent, of the sulphur from this 

 ore would be liberated. Therefore a simple calculation will 

 show that for each ton of ore about 838 pounds of sulphur or 

 1676 pounds of sulphur dioxide would be given off into the 

 atmosphere. The author has been informed that the smelter 

 extracts 1000 tons of ore per day. If such is the case it 

 will be seen that the enormous quantity of 1,676,000 



