4 W. H. Brewer—Suspension and Sedimentation of Clays. 
liquid be decanted from the sediment, an enwal pansy, of dis- 
tilled water be added and the mud again by agitation, 
the clay again allowed to settle, the laGhd, seas decanted 
when clear, and this shige repeated over and over, the salt- 
the conditions which take place in_ the erosion and transporta- 
tion of muds by rivers and their ultimate deposit in the sea. 
From such experiments we may say in a general way, that 
the more saline the suspending water, the more rapid the sedi- 
mentation, but the rapidity of preciptation is not directly pro- 
portionate to the quantity of salts dissolved. Reducing the 
saltness one-half does not double the time of precipitation, and 
the precipitation is comparatively rapid until the solution is 
very weak indeed. With some clays the precipitation is as 
complete in thirty minutes in sea water as in thirty months in 
distilled water. This completeness of precipitation refers to 
the actual clearing of the liquid, and not the rate of deposition 
of the first and heavier portions. 
e experiments are more striking if conducted with acids, 
they acting with greater intensity than salts. The successive 
henomena are similar in character, and differ only in degree, 
the later changes are more Far and the final suspension is 
more striking. For example, if we begin with a strong solu- 
tion of sulphuric, nitric and chlorhydric acids mixed, and Wess 
low through repeated dilutions as above described, the floce 
lation and Lhe guanoniay of the suspended material is Koes 
long suspension of clays is best seen in specimens that have 
thus undergone treatment with acids or salts, and then washed 
with distilled water through successive dilutions. 
The behavior of these finer suspensions is analogous to that 
of a colloid. The diffusion through water is like that of a 
colloid, and when the finer portions are evaporated tows and 
at low temperatures, they are at first very bulky _ Spee 
in appearance, shrinking enormously on drying i 
curiously like some organic colloids. If the clay is jot pete 
