1876.] 



Forms assumed by Drops of Liquids. 



271 



The same height of fall on smoked glass gave a rather wider spreading 

 out than in I ; after which the phases differed only from those depicted in 

 the arms being thinner in the necks, with bulby heads, and the drop finally- 

 breaking into three when it rose vertically. 



Set 7. 



Unsmoked glass. 150 millims. 



I. The phase I was seen, after which drops disposed as in fig. II were left on tJie 

 plate, indicating that the arms from which the small drops split, split a 

 second time, while the rest did not. The figures were of much tlie same 

 type as when the fall was 100 milhms. 



A later stage of II, Set 6, was seen, more contracted, and with a com- 

 plete circle of small drops round it, left from the first spreading out. 



Set 8. 



Smoked glass. 150 millims. 

 I. Very much spread out, flat, and uniform, with tendency to irregular small drop- 

 forming arms. 



Ila is the central vertical section from rim to rim of II. 



III. The central patch begins to tear. 



IV. The ring splits off, and the torn central patch runs together into arms ; or the 



alternative course indicated by the next five figures is taken. 



Illa. Sometimes the centre contracted till the arms met. (In the case of milk from 

 280 millims., whose forms, it has been remarked, were similar to these, the 

 centre invariably contracted till the arms met ; the arms were also beaded, 

 as if tending to split into groups along their whole length.) 



IVa. The central patch tears open into a ring, into which portions of the arms 

 contract. 

 Va. The ring splits into drops. 



Later stages showed a general distribution of drops over the plate, rather 

 hard to remember with certainty, even immediately after they were seen, 

 with occasional small arms remaining somewhat as in the figs. Via & VI/3. 



From 255 milhms. on unsmoked glass the forms were much the same as 

 from 100 and 150 millims. The arms of fig. II, Set 6, were seen, 6, 8, and 

 12 in number, and rather longer than there drawn. Occasionally the 

 centre tore, and concentric rings of drops were formed. 



Set 9. 



Smoked glass. 250 miUims. 



The phases were generally the same as from 150 millims. (Set 8), with 

 the variations of figs. I & II. 



Later, the whole mass of central arms, or thin layer of liquid, split up 

 into fine drops, which rose in a splutter from the plate. 



It is to be observed that while on unsmoked glass the type of forms hardly changes 

 while the fall increases from 100 to 250 millims., the same increase of fall on smoked 

 glass is accompanied by very marked alterations in the behaviom* of the drop, and that 

 generally the wider spreading out of the drop on smoked glass indicates much less 

 friction than on unsmoked. 



TJ 2 



