330 John Casper Brafiner 



ANALYSIS OF ARKANSAS RIVER SEDIMENT.* 



Per cent. 



Silica (SiO,) 69-53 



Alumina (Al.Oj) 11.65 



Iron (ferric) oxide (Fe^O^) 4-46 



Carbonate of lime (CaCo,) 6.62 



Carbonate of magnesium (MgCOj) 3.52 



Potash (K,0) 66 



Soda (Na,0) i.i4 



Organic and volatile matter 2.95 



Total 100.58 



These analyses, together with a large number of washings 

 of the sediment, show that its chief constituent is quartz sand. 

 There is always more or less clay in the water. 



The Finer Sediments. — Experiments have already been made 

 by other observers which show that extremely fine material 

 held in suspension by water may be retained in suspension for 

 an indefinite length of time.* The observations upon Ar- 

 kansas River water point to the same conclusion. A glass jar 

 one metre in length and holding six litres, was filled with tur- 

 bid water taken from the river October loth, 1887, and was 

 allowed to stand in the Survey ofiice until January i6th, 1888. 

 Within four days after it was filled the water had become com- 

 paratively clear. Very fine particles continued, however, to 

 float about in it until January 15th. That night the weather 

 was cold enough to freeze and feathery ice crystals penetrated 

 the whole body of the water. As soon as the room was warmed 

 and the ice melted, the matter in suspension was found to be 

 collected in masses resembling strings of cobwebs, in which 

 form it clung to the sides of the jar or sank to the bottom, 

 leaving the water perfectly clear. 



Dissolved Matter. — The matter in solution bears no constant 

 relation to the volume of water, though in a very general way 



* Analysis by Assistant, Dr. J. P. Smith. 



tOn the subsidence of particles in liquids, by Prof. Wm. H. Brewer, 

 Memoirs Nat. Acad. Sci., Vol. II, p. 165. 



Subsidence of fine solid particles in liquids, by Carl Barus, U. S. Geo- 

 logical Survey, Bulletin 36, 1S86. 



