18 0. B. B0GGILD. BOTTOM DEPOSITS. [norw. pol. Exp. 



nature of the deposits in such places will thus, to a very great extent, depend 

 upon the nature of the coast rocks. As those, however, of the north coast 

 of Siberia, consist in great measure of clay deposits, morainic or stratified, 

 the sea-bottom north of Siberia will, on the whole, be covered with a parti- 

 cularly argillaceous deposit. 



The aim of the washing is in the first place, to try to find out the laws 

 which have governed the distribution of the various deposits upon the sea- 

 bottom. This is in contrast to washings performed for agricultural purposes 

 where it is a question of the practical use of the clay, and where the aim 

 of the washing is to get it as fine as possible. Here the ideal to be aimed 

 at would be to get the clay washed out in exactly the degree of consi- 

 stency in which it was deposited in nature, so that whatever had sunk 

 in a coagulated condition could be retained in the same state, and 

 thus come among the coarser particles. In practice this is scarcely possible. 

 It is not unreasonable to suppose that the clay particles that fall upon the 

 sea-bed in a very finely distributed condition, acquire, upon coming into 

 contact with the other clay particles, exactly the same consistency as the 

 clay that has sunk to the bottom in a coagulated condition. It 

 should moreover be remembered that as time passes, the clay upon 

 the sea-bottom will scarcely remain in the condition in which it was originally 

 found. In all older deposits, the clay continues to become more compact, 

 chiefly owing to the percolating water, which probably endeavours to cement 

 it more and more together. As the extent of this operation is exceedingly 

 varied in the various parts of the sea-bottom, the result is that the clay taken 

 up in bottom-samples will be of a consistency that has little connection with 

 the conditions under which it was originally deposited. The chief result 

 obtained by the washing is thus to find out the proportion between the total 

 amount of clayey substance on the one hand, and of true mineral particles 

 on the other, and further the proportion between the various sizes of the 

 latter. It is clear, therefore that in order to attain this, special importance 

 must be attached to the measurement of the percentage of clay and sand of 

 each separate size of grain, with the greatest possible accuracy. 



In the actual washing, the salinity of the water will now play a very 

 important part. As all the samples when taken are saturated with salt, this 

 will be capable of disturbing the rate of washing to quite an extraordinary 



