ARSENIC CONTENT OF FOEAGE CROPS. 



55 



Both in a southerly and in a westerly direction, in 100 per cent of 

 the cases examined, the leaves and the ash of the injured trees con- 

 tained larger percentages of sulphur trioxid than the leaves and the 

 ash of uninjured trees. 



The observations made on the inspection tours in various direc- 

 tions from the Washoe smelter considered in connection with these 

 figures prove that the forests on public domain had been injured and 

 were being injured by sulphur dioxid fumes previous to and during 

 the summer of 1908. 



ARSENIC CONTENT OF FORAGE CROPS AROUND WASHOE 



SMELTER. 



The previous investigation made around the Washoe smelter in 

 the summer of 1906 showed that the ores smelted contained arsenic, 

 some of which escaped from the stack and settled on the surrounding 

 vegetation. The investigation in 1908 was made to determine 

 whether this arsenic settled on the range grass of the public domain. 

 For purposes of investigation 33 samples of range grass were col- 

 lected at distances varying from 2j to 15 miles from the smelter in 

 different directions. All samples except one were taken from the 

 public domain or National Forest land. As in the 1906 investiga- 

 tion, determinations were made of total and w^ater soluble arsenic 

 and the results obtained calculated to the dry basis and expressed 

 both as milligrams of arsenious oxid per gram of dry sample and as 

 grains of arsenious oxid per daily ration of 25 pounds. The results 

 obtained are given in Table XIV. 



Table XIV. — Arsenic content of range grass expressed as arsenious oxid, nearly all 

 samples taken from National Forest or public domain. 



(Calculated to dry basis.) 



1^ Protected by hill. 



