30 



The parts of the samples which are below 0'5"^™ in size 

 were separated by washing into three parts 1) containing the 

 ingredients below 0-01°i°i, 9) those from O'Ol— 0-05^™ and 

 3) those from 0*05 — 0*5°i'". The exactness which may be 

 attained by the washing is perfectly satisfactory between the 

 size-limits of the two last named ingredients, but not between 

 the size-limits of the two first sizes of grains. However re- 

 cently deposited the clay may be, it is always very difficult to 

 get it finely divided by boiling, and the various samples are 

 very unequal in this respect. By long and repeated boiling, one 

 may perhaps in most cases succeed in getting the clay sub- 

 stance broken up , but the results thus attained will certainly 

 not correspond exactly with the natural conditions under which 

 the deposits were laid down. 



As mentioned above clay is deposited much quicker in salt 

 than in fresh water. The reason of this, as shown by experi- 

 ment, is, that the single particles of clay, by coming into salt 

 water, clot together into somewhat large, coherent masses, 

 which as a rule, however, do not attain the size of 1^^. This 

 clotting only takes place to a very slight degree or not at all, 

 if the clay is very finely divided, as will generally be the case 

 if the clay originates from coast erosion or from coast rivers. 

 Glacier-rivers, however, will often convey the clay in great quan- 

 tities, and when it is washed into the sea by them the greater 

 part of it will be deposited very quickly. 



If we now take the samples singly, the clay in them will 

 originally have been deposited in somewhat different ways. 

 One part of it will have been deposited very slowly, and must 

 thus be classified amongst the very finest ingredients of the sample. 

 Another part has sunk to the bottom comparatively quickly, and 

 must therefore be classified among the somewhat coarser ingre- 

 dients, between 0-02 and О'Об"^'". It is very doubtful whether 

 it is possible by washing, to separate even approximately the 

 various parts of the clay from each other. It is most probable 



