NO. 14.] 



C. J. J. FOX. ANALYSES OF BOTTOM DEPOSIT. 



57 



The results of these few analyses appear to agree very well under the 

 circumstances with those obtained by Heidenreich, except in the case of one 

 Iron estimation ; and it may be assumed that the methods adopted give quite 

 reliable results. It is commonly believed that in a clay deposit graduating 

 from brown to grey through grey-brown and brown-grey, the ratio of Ferrous 

 to Ferric oxide found, should alter simultaneously with the change of colour 

 — the Ferrous oxide giving to the clay its grey-green and the Ferric oxide 

 its brown colouration. And this may on the whole be said to hold in the 

 case of the samples here under consideration, with possibly just one exception. 

 This exception however, happens to coincide with the above mentioned 

 discrepancy in the two Iron estimations of Heidenreich and myself. As will 

 be seen from Heidenreich's analysis, a greyish sample appears to have a 

 higher percentage of Ferric iron than a brown layer of the same clay; my 

 analysis on the other hand seems to indicate the exact contrary. In view of 

 the fact that the samples have been all used up, it is now impossible to 

 decide which is right for certain, but inasmuch as the former result appears 

 unlikely and the latter what might be expected, it seems at all events safe to 

 say that so for as is known a brown layer probably does contain more 

 Ferric iron than a grey layer of the same clay. 



Kristiania, May 27 tb 1905. 



