BOOKS AND CURRENT LITERATURE 25 



Unconnected with sulphur dioxide injury but of general interest is 

 the discovery of the Commission 'ts agronomists^ that small quantities 

 of both lead and arsenic are of normal occurrence in the soils of the 

 region and in certain other California soils. The amounts found and 

 not believed due in any degree to contamination from the Smelter, 

 range from to 10.0 parts per million of lead and from 0.2 to 8.0 parts 

 per million of arsenic. These amounts are believed far too small to 

 have significant agricultural effect, in which conclusion an attached 

 statement of Prof. Charles B. Lipman agrees. The delicate analj^tical 

 methods necessary to the investigation are described and there is a 

 brief review of the literature of the occurrence of lead and arsenic in 

 soils. Elsewhere in the report analytical methods are described for 

 arsenic and lead in plants and in air dust and for sulphur in plants, 

 also very careful and accurate methods for the determination of sulphur 

 dioxide in air. There is also a series of experiments on the perception 

 by man of small amounts of sulphur dioxide in the atmosphere. Of 60 

 persons tested nearly all could detect 4 parts per million of the gas and 

 most of those previously acquainted with its odor could detect 3 parts 

 per million. No one detected 1 part per million. Appended to the 

 report is an annotated bibliography of 96 titles covering the effect of 

 sulphur dioxide on vegetation and animal life. — E. E. Free. 



3 Charles F. Shaw and E. E. Free, pp. 454-462. 



