NO. U.] MECHANICAL COMPOSITION OF THE SAMPLES. 



II. 

 MECHANICAL COMPOSITION OF THE SAMPLES. 



The material submitted to me for examination consists of samples from 

 16 different localities, most of which are situated along the north coast of 

 Siberia, while the remainder of the samples have been taken from the bottom 

 of the deep North Polar Basin, more or less distant from land. From some 

 of the first-named localities, there are two or more samples, taken at different 

 hours on the same day, and they frequently present very great differences, 

 and give a very characteristic illustration of the rapidity with which the 

 nature of the bottom may change in the neighbourhood of land, even in ad- 

 jacent spots, according as the depth becomes greater or less. The distribution 

 of the samples may be seen from the accompanying chart, Table I, in which 

 the stations are numbered in chronological order, and to which constant 

 reference is made in these pages. The samples will be designated by their 

 numbers, and the addition of letters will indicate the various samples from 

 the same locality. 



The samples were preserved either in alcohol, or in a dry condition. 

 We do not know at present whether this difference has any influence upon 

 the washing-results. It is possible that by being dried and kept for some 

 time, the clay may become rather more coherent than it originally was, so 

 that a wrong idea of the mechanical nature of the samples may be obtained. 

 As far as I am aware, nothing has yet been proved with regard to this circum- 

 stance; but when we consider how easily dried samples such as these, become 

 soft in water, it would seem as if the degree of coherency attained by the 

 clay in drying, can be only very small. Upon the whole, the mechanical 



