44S 



Prof. Guthrie on Drops, 



[Recess, 



turned up at the end, and touches a plug of cotton wool at G. The 



sphere H, from which the dropping takes place, is hung by three thin 

 wires from the ring of a retort-stand. The upper half of the sphere is 

 clothed in cotton wool, which reaches up to the plug at G. The whole 

 arrangement is placed upon a separate table from that which supports the 

 balance, so as to avoid the vibration caused by opening and shutting the 

 balance case. The drops which fall from H enter the funnel L, whose 

 lower end is somewhat bent, so that the drops are thrown out of the ver- 

 tical, and all upward splashing avoided. The rapidity of the flow through 

 the siphon, and consequent dropping from H, is regulated by raising or 

 lowering the table C. The vessel A acts as a regulator for keeping the 

 level of the liquid in B at a constant height. 



The first series of experiments was made with the double object of 

 determining how far the rapidity of dropping influenced the size of the 

 drops, and to establish the uniformity of the size of the drops which drop 

 at equal intervals of time. 



In these experiments cocoa-nut oil was taken as the liquid, an ivory 

 sphere as the solid, and atmospheric air as the gas. The ivory sphere was 

 washed in hydrochloric acid, so as to deaden its surface. Immediately 

 before and after each batch of drops, the same number of drops were 

 counted, and their time of falling compared with the time which elapsed in 

 the actual experiment. In no case, however, was there a diff'erence between 

 the two of a single second, so that gt may be considered in each case to be 

 exactly given. 



Table I. — Cocoa-nut oil. 

 T =28°-5 C. 

 gt= 1". 



Radius of ivory sphere =22* 1 millims. 



Number 

 of drops. 



gt. 



Weight of drops. 



60 

 60 

 60 

 60 

 60 

 60 

 60 

 60 



ti 

 1 

 1 

 1 

 1 

 1 

 1 

 1 

 I 



gramme. 

 3-9817 

 3-9841 

 3-9784 

 3-9807 

 3-9742 

 39730 

 3-9735 

 3-9682 





gf. 



Mean weight of single drop. 





1" 



0-066279 



Preliminary experiments having shown that the size of a drop is greatly 

 affected by the rate at which the dropping takes place, that is, by the time 

 occupied by the drop in its formation, the following experiments were per- 

 formed to establish the connexion between the two. 



It may be here remarked that with some liquids, of which cocoa-nut oil 



