THE EFFECT OF SOOT ON VEGETATION. 21 



under a dark chamber sealed around the bottom with oiled 

 clay. Daily applications of soot were made for seven days. 

 At the end of two weeks observations were made. Quanti- 

 ties of soot used of Sample C were as follows: Case No. 

 1, 3.78 gm. per square meter. No. 2, 2.97 gm. per square 

 meter. No. 3, 3.24 gm. per square meter. No. 4, Control. 

 At the end of the experiment the only visible difference 

 was an apparent checking of growth in the case of the 

 plants treated with soot. This condition became more ap- 

 parent when the plants thus treated were allowed to grow 

 in the open for a few days. 



SOOT FALL FOR WOODLAWN, 



In addition to other data obtained open glass jars 

 twelve inches deep and four inches in diameter were placed 

 at each station under observation and analysis made of 

 the matter collected in each jar placed in the region of 

 Woodlawn. Similar records were made for various sta- 

 tions in Pittsburgh and are given in another report of this 

 investigation. 



STATION AT 3. 



Total deposit for 4 months, June, July, August and 

 September, 1912, was 1.1442 grams 93 tons per square 

 mile per year. 



ANALYSIS. 



Tar, 1.86% 



Fixed carbons, 28.34% 

 Ash, 68.8 % 



Iron in ash, 12.7 % Fe2Os. 



STATION AT 5. 



'Samples taken July, June and October, 1912. Other 

 samples not good (contained leaves and bugs). 



Total weight of solids 6.6250 grams 68 tons per 

 square mile per year. 



ANALYSIS. 



Tar, 6.5% 



Fixed carbons, 41.1% 



Ash, 51.4% 



Iron in ash, 8.3% 



