Feb., 1919] Salt, Iron, and Acidity of the Ash 



225 



of hot water, until the filtrate approximated 500 cubic centi- 

 meters. This water extract was then made up to exactly 

 500 cubic centimeters and 100 cubic centimeter portions used 

 for the analysis. The acidity was determined by titration 

 against N/100 NaOH and calculated as H2SO4, the ferrous 

 •iron by titration against N/20 KMnO^. The ferric iron was 

 also determined in Samples No. 1 and No. G by reduction with 

 zinc and sulphuric acid and titration against KMn04. The 



Photograph by D. B. Church 



FLOOD BORNE SILT AROUND KATMAI CHURCH. 



This appeared to be a favorable situation for the beginning of revegetation, but 



it was found by experiment that the soil was toxic to wlieat plants. 



Tlie analysis showed 0.558% of ferrous iron. 



increase in the amount of KMn04 used in this titration, over 

 that in an equal volume before reduction, gave a measure of the 

 ferric iron. The water soluble sulphate was also determined in 

 these two samples by precipitation as BaS04. The accompany- 

 ing table contains the results of the analysis. 



Ferrous sulphate is not only directly injurious to plant 

 growth, but by inhibiting the action of nitrifying bacteria 

 indirectly cuts off the supply of an essential food. The presence 

 of this toxic compound, together with the low nitrogen content 



