640 Journal of Agricultural Research voi. x, no. 12 



remain over a saturated piece of blotting paper), a medium layer of 

 water (such as would remain upon a clean, level glass plate) and a very 

 thick layer of water (as that in a petri dish) were observed. 



In the earlier work a large pane of glass ruled with a series of con- 

 centric arcs varying successively, 2 inches in radius, similar though on a 

 much larger scale to the Jeffers counting plate used in bacteriological 

 laboratories, Vv^as used to determine the number and position of the 

 splash drops. Later two such panes of glass placed end to end v/ere 

 used and these afforded a total distance of 114 inches, which serv^ed all 

 needs until the wind factor was introduced. At the latter stage of the 

 work acetic acid was applied to the point of impact by a finely drawn 

 siphon and with neutral or slightly alkaline litmus blotters 6 inches 

 square placed in the path of the wind the limits of splash were easily 

 determined. 



The level surface used at the plane of the counter was supported upon 

 two strips of glass placed across a small tray. When inclined surfaces 

 were used, or the level surface elevated above the counter, a glass plate 

 was placed in a clamp and fastened to a ring stand. The level plates 

 were adjusted with a spirit level and the inclined ones were placed at 

 definite angles to the level plate, as is noted below. The blotting paper 

 surfaces were always placed upon a glass plate whether used dry or wet, 

 level or inclined. 



NATURE OF A SPLASH 



A single drop falling 12 inches onto a clean dry glass plate does not 

 cause a splash. This was repeated 100 times with each size of drop 

 with the same result. The same is true of a drop falling 24 inches, 

 while at 48 inches the largest drop (o.i c. c.) did break in a few instances 

 and scatter splash drops over the counter. When, however, two drops 

 fall consecutively upon the same spot, even the smallest (0.02 c. c.) 

 will cause a splash when falling but 12 inches. 



This experiment, repeated with pieces of dry blotting paper, gave the 

 same result in the case of single drops, though with the largest drop 

 falling 12 inches an increasing number of splash drops appeared after 2, 

 5, and 10 drops were allowed to fall upon the same place, showing that 

 the nearer saturated the blotting paper became, the more water became 

 available in the surface film, and this was broken up and scattered by 

 the impact of the falling drops. 



A dilute eosin solution was applied to the surface of the glass plate 

 and the saturated blotting paper in many of the experiments, and in all 

 such cases the stain appeared upon the counter. When acetic acid was 

 supplied to the plate at the point of impact as mentioned above, one 

 never failed to note the change of color of the litmus paper where splash 

 drops fell upon it. 



These facts justify the conclusion that the splash drops scattered from 

 the point of impact of a falling drop are made primarily of the water 



