CONTENTS 



Page. 



Introduction 7 



Process of extracting metals from ores 7 



Resultant wastes 8 



Experimental investigations relating to the action of sulphur dioxid on vege- 

 tation 10 



Organs of plants through which injury takes place 10 



Amount of sulphur dioxid that may cause injury 11 



Sulphur trioxid content of the foliage of fumigated and unfumigated 



plants 13 



Field investigations of the action of sulphur dioxid fumes on vegetation 14 



A California smelter and certain foreign smelters 14 



Two Tennessee smelters 15 



First investigation of injury by smelter wastes around Anaconda, Mont., 1906-7. 21 



Location of smelter and appearance of surrounding vegetation 21 



Sulphur trioxid in foliage of trees around Washoe smelter 25 



Injury to cattle by arsenic in the vicinity of Washoe smelter 29 



Injury to crops and soil by tailings and slag from the Washoe reduction 



plant 32 



Second investigation of injury by smelter wastes around Anaconda, Mont., 



1908-9 36 



Appearance of vegetation surrounding smelter 37 



Sulphur trioxid in foliage of trees around Washoe smelter 45 



Arsenic content of forage crops around Washoe smelter 55 



Methods of analysis used in investigations 57 



Foliage of trees 57 



Soils 58 



Waters 60 



Cattle-food materials 61 



Ores 62 



