478 



Prof. Guthrie on Drops. 



[Eecess, 



This scheme is' verified by the experimental results obtained. Of all 

 liquids water forms the largest drops in falling through air, because in it 

 the stubborn cohesion prevails to the greatest degree over the joint action 

 of persistent cohesion and weight. In water mercury forms drops greater 

 than in all other liquids, because in water (as a medium) stubborn cohesion 

 and weight prevail to the greatest degree over persistent cohesion. 



The case SLL may be inverted if the drop-forming liquid be specifically 

 lighter than the medium liquid. Thus every case of SLL which we have 

 examined in which a liquid, A, drops downwards through a liquid, B, has a 

 counter case in which the liquid B drops upwards* through the liquid A. 



In order to measure the size of such ascending drops, the stalagmometer 

 (fig. 7) is modified in form. It is not found possible to cause the dropping 

 liquid to adhere with sufficient completeness and uniformity to a solid 

 sphere immersed in the denser medium, in the cases experimented on. 

 The end of the siphon A was turned upwards, and served as the solid 

 whence the liquid dropped, without the interposition of a sphere or other 

 solid. The measuring-tube D was removed from the neck of the cup 0, 

 a stopper being inserted in its place. The cup C was filled with water, 

 and the measuring-tube D, being also filled with water, was inverted into 

 it and supported by the holder H. The modified stalagmometer is seen 

 in Plate Y. fig. 10. Care was taken that the end of the siphon A should 

 always be at the same depth beneath the surface of the water in C. 



The drop-sizes of the liquids of Table XVI. were first examined by this 

 stalagmometer. 



The following Table XVII. shows the number of drops of the various 

 liquids, dropping through water, required to fill the measuring-tube up to 

 the given mark. The measuring-tube employed was different from that 

 used in forming Table XVI. On this account, and because the deliver- 

 ing solid was quite different in shape, and gt only 2", no immediate com- 

 parison can be made between Tables XVII. and XVI. In Table XVII. 

 correction is made for meniscus. 



Table XVII. 



T=24°-2C. 

 T. BT^. BT. B^T. B. 



287 252 229 205 103 



287 252 231 205 104 



287 251_ 230 207 104 



287 251-7 230 2057 103-7 



We gather from this Table a law quite similar to that deduced from the 

 measurement of the size of the downwards moving drops of water through 

 these same liquids. It is as follows : — 



The drop-size of any mixture of two liquids, A and B, dropping up- 

 ^ See Part I. Introduction. 



