482 



Prof. Guthrie on Drops. 



[Recess, 



In like manner, comparing the drop-sizes of Table XX. with one an- 

 other, or with Wb, we have 



Table XXI. 



Wt 86-2 



^1^=2.541. 



Wbt, 86-2 

 Wb ^ 177-5 

 Wbt ■ 86-2 

 Wb ^ 163 



Wb,t~ 86-2 

 Wb 86-2 



2-059. 

 1-890. 

 1-000. 



Wb 86-2 



Lastly, on comparing these figures with those of Table XX., we get 

 the remarkable law, which it would be difficult to express in words, that 



Wb.Tw Wb.BT^w Wb.BTw Wb.B^Tw 



Wt.Bw Wbt,.Bw Wbt.Bw Wb^.B, 



= 1 nearly. 



The main results with regard to drops may be collected into the follow- 

 ing laws : — 



SLG. 



Law 1 . — The drop-size depends upon the rate of dropping. Generally, 

 the quicker the succession of the drops, the greater is the drop ; the slower 

 the rate, the more strictly is this the case. This law depends upon the 

 difference, at different rates, of the thickness of the film from which the 

 drop falls. 



Law 2. — The drop-size depends upon the nature and quantity of the 

 solid which the dropping liquid holds in solution. If the liquid stands in 

 no chemical relation to the solid, in general the drop-size diminishes as 

 the quantity of soHd contained in the liquid increases. The cause of this 

 seems to be that the stubborn cohesion of the liquid is diminished by the 

 solid in solution. Where one or more combinations between the liquid 

 and solid are possible, the drop-size depends upon indeterminate data. 



Law 3. — The drop-size depends upon the chemical nature of the drop- 

 ping liquid, and little or nothing upon its density. Of all liquids exa- 

 mined, water has the greatest, and acetic acid the least drop-size. 



Law 4. — The drop-size depends upon the geometric relation between 

 the solid and the liquid. If the solid be spherical, the largest drops fall 

 from the largest spheres. Absolute difference in radii takes a greater 

 effect upon drops formed from smaller than upon those formed from 

 larger spheres. Of circular horizontal planes, within certain limits, the 

 size of the drop varies directly with the size of the plane. 



Law 5. — The drop-size depends upon the chemical nature of the solid 

 from which the drop falls, and little or nothing upon its density. Of all 



