King—The Suspension of Solids in Fluids . 279 
is to be presumed tihat tbe thickness of the water film which 
would be controlled by the individual sand grains, when in sus¬ 
pension in water, would exceed the 8 to 15 thousandths of a 
millimeter computed. 
There is another quite different set of phenomena which, 
likewise, appears to be most simply explained by a retained film 
of fluid about the surfaces of immersed solids. The law of 
flow of fluids through capillary tubes affirms that the volume 
per unit time is directly proportional to the effective pressure; 
but our own observations on the flow of water and of air through 
porous media recorded in the 19th Annual Report of the U. S. 
Geol. Survey, showed that of 44 capillary tubes experimented 
with 16 gave flows, throughout the entire range of pressure, 
increasing faster than the pressure while most of the others gave 
flows increasing faster than the pressure through a portion of 
the series. Of 55 comparisons of flow through wire gauze, 
under a water presure of 1 centimeter to 30 centimeters, in all 
but 5, the flow increased faster than the pressure. Of 147 com¬ 
parisons of the flow of water through sandstone under a pressure 
of 21 centimeters to 1,055 centimeters of water, in all but three 
cases the flow increased more rapidly than the pressure. Of 
132 comparisons of the flow of water through sands under 
pressures from 1 centimeter to 1,150 centimeters of water, in 
100 of these the flow increased faster than the pressure. The 
flow of water has increased faster than the pressure by amounts, 
with sands, ranging from 0 to 45.79 per cent; with rock from 
0 to 85.9 per cent and with capillary tubes from 0 to 20.9 per 
cent. 
Of 59 comparisons of the flow of air through sand, dust shot, 
bundles of knitting needles and capillary tubes, under pressures 
ranging from 1 millimeter to 50 millimeters of water, in all 
but 10 cases the flow increased faster than the pressure. Of 
121 comparisons of the flow of air through capillary tubes 
Meyer found 64 cases where the flow increased faster than the 
pressure; 52 cases where it increased slower than the pressure 
and but 5 cases of strict agreement with the law. 
Finally, with all the observations of all observers, whether 
using sands, rock or capillary tubes; whether with high or low 
