176 Mr. T. Tate on the Magnitude of a Drop of Liquid 



niferous particles towards the refracting surface increases with an 

 increasing angle of incidence. 



In vertical incidence, the rays polarized perpendicular to the 

 plane of incidence must be affected just like the rays polarized pa- 

 rallel to it, since in both the oscillations of the aether lie in the re- 

 fracting surface. For oscillations perpendicular to the plane of 

 incidence, there is no, or only a very slight difference of phase pro- 

 duced by different angles of incidence ; but it is otherwise in the 

 component having oscillations parallel to the plane of incidence, 

 and in which the inclination of the paths of the luminiferous 

 particles towards the refracting surface alters. 



Now, since these researches show that this alteration is greatest 

 in light polarized parallel to the plane of incidence, and in- 

 creases with increasing angle of incidence, this property of light 

 transmitted through metals leads to the same conclusion as the 

 properties of light reflected from metals, namely that the oscilla- 

 tions of the luminiferous aether follow the plane of polarization. 



Finally, it may be remarked that, by means of Babinet's com- 

 pensator, the author was unable to detect any difference of phase 

 in the components, polarized parallel and perpendicular to the 

 plane of incidence, of the light which had previously passed 

 through transparent substances such as plates of glass. There- 

 fore the analogy between metals and transparent bodies, which 

 Jamin has proved for reflected light, is not maintained in rela- 

 tion to transmitted light. 



XXX. On the Magnitude of a Drop of Liquid formed under 

 different circumstances. By T. Tate, Esq.* 



PEOPLE generally, and medical men especially, speak of a 

 drop of liquid as if it were some definite quantity, whereas, 

 as the results of the following experiments show, its weight 

 varies not only with the diameter of the tube in which it is 

 formed, but also with the density, temperature, and chemical 

 composition of the liquid. The particles of a liquid are retained 

 in the form of a drop by the force of adhesion subsisting between 

 these particles and the sides of the tube, or the substance on 

 which the drop is formed ; and opposed to this force is that of 

 gravity and the cohesion amongst the particles of the liquid : 

 when the drop attains a certain magnitude, the force of gravity, 

 acting upon it, counterbalances that of adhesion, and then the 

 liquid falls. Any change of conditions, therefore, affecting these 

 forces must influence the magnitude of the drop. Under the 

 same circumstances, the weight of a drop of liquid, as deter- 

 mined by experiment, is remarkably uniform, not varying in any 

 * Communicated by the Author. 



