218 



The Ohio Journal of Science [Vol. XIX, No. 4, 



most probably a composite sample of the ashfall, formed by the 

 slumping of large masses down the slopes of Katmai immediately 

 following the eruption. The analyses listed in Table II were 

 made upon representative samples of the surface ash contami- 

 nated very little, if at all, from the pre-eruptive soil. There 

 may have been some admixture however, for the strong winds 

 of this region drift the ash for long distances, and have laid bare 

 the old soil on the exposed ridges and hills. The relatively 

 high total nitrogen content of (11) might well be due to wind 

 borne humus from the old soil, that found lodgment for the time 

 being upon the moist top layer of the finely divided Katmai ash. 



TABLE III. 

 Nitrogen Content of Some Miscellaneous vSamples of Ash. 



1917. (1) Katmai River wash, seedling grass 



Aug. 15. growing; cf. (5), pp. 226 and 229 



(2) Same, and close to (I), but seedlings 



died; cf. (6), pp. 226 and 229 



Sept. 15. (3) Kodiak Island, Pillar Mountain, Veg- 

 etation Station No. 14; cf. (4), pp. 



226 and 229 



1916. (4) Sample 33, Katmai Church, stream 

 borne; cf. (1), pp. 226 and 229 



Parts Nitrogen per 100,000 



NH" 



0.04 



trace 



0.012 



NO2 



0.0004 

 trace 



trace 



Total N. 



3.20 

 3.20 



O.SO 

 6 10 



The analyses included in Table III were made for the 

 purpose of ascertaining whether the nitrogenous plant food in 

 the ash was the determining factor controlling vegetation. 

 The results must be interpreted in conjunction with the ferrous 

 iron and free acid content of the same samples included in 

 another paper-, although the nitrogen content of (1) and (2) is 

 very small and any difference appears to be in favor of (1), 

 yet in the light of the ferrous iron content the difference in 

 vegetative growth must be attributed to the well known toxic 

 effects of this compound. The ash designated by (3) in the 

 table was a wind blown drift on the flank of Pillar Mountain, 

 Kodiak Island, on which, after five years, little or no vegetation 

 had returned. Free sulphuric acid and ferrous sulphate were 

 found in this sample also, but not to the same injurious extent 



^Shipley, J. W Scientific Results of the Katmai Expeditions. VI. The Water 

 Soluble Salt Content, the Ferrous Iron Content and the Acidity of Katmai Vol- 

 canic Ash. Ohio Journal of Science, 19: 224-229, 1919. 



