86 The American Geologist. January, 1896 
the angularity of the grains is conducive to the floating of 
the sand is shown in the first table given. 
All my experiments heretofore having been made with 
water from cither the Llano or Colorado rivers, it occurred t<> 
me that possibly a difference might he noticed in the surface 
reaction should other water he employed. I accordingly re- 
peated several of my tests using rainwater. Colorado river 
water, boiled and filtered, and distilled water with little or no 
appreciable difference in the results. 
The second part of the phenomenon, or. as I am inclined t<> 
regard it, the second phenomenon, is the formation of patches 
or rafts from the floating grains. Here the investigator en- 
counters another difficult, yet interesting, problem in capillar- 
ity, viz.: The attraction, though largely apparent, existing 
between small bodies floating on a liquid. Leaving gravita- 
tion out of consideration the usual explanation ottered is 
as follows: The floating sand grains are not wet by the 
water and when brought sufficiently near one another the de- 
pressions, in which they rest, unite thus leaving between 
them an interval in which the water is below the general sur- 
face, hence by the pressure of the surrounding liquid they 
are urged together.* 
It seems to me, however, that the so-called attraction be- 
tween the individual sand grains, as shown in the formation 
of rafts, is exerted over a greater distance than could be ac- 
counted for in the explanation above given. Thus 1 find 
that on an undisturbed surface of water they are brought to- 
gether when separated by an interval as great as 4 cm., and 
that when scattered over the surface of a basin of water a 
foot in diameter they will finally form a single raft. 
The observations made by Mr. Graham on the Connecticut 
river enabled him to reach the following conclusions: 
1. They show that coarse sand can be floated away on a 
current of far less velocity than OA'yi't miles per hour. 
2. They show a method of removing sand from the lower 
side of a forming bar which has gotten above high water 
mark. 
*For another and ingenious explanation see the paper by the late 
professor John LeConte on "Apparent attractions and repulsions of 
small floating bodies." Ainer. Jour. Sc, HI. vol. xxiv, p. 416, Dec. 
L882. 
