VISCIDITY OF WATER. " 55 



A spherule of mercury of a proper size to be supported or let fall from 

 by water, at its surface, if placed gently there, would not Jo? great a 

 fail to make its way through the pellicle of the water, if 

 let fall from too great an height. 



All the preceding experiments were repeated with a The experi- 



stratum of essential oil of turpentine, and afterwards with ^^^^^ answer 



^ , ^ ■» . 1 equally well 



one of oil of olives, placed on the water contamed m the ^hen oil is 



glass instead of the ether, and the results were in all res- poured on the 

 pects similar. I thought however that the spherules of^j^^^j^gj. 

 jflercury which were suspended upon the water were ra- 

 ther larger when the surface of the water was covered 

 with oil than with ether ; and in the experiments made 

 with the powder of tin, poured on the oil, the finest parts 

 of the powder, in very small quantity, floated on the sur- 

 face of the oil. 



EXPERIMENT IV. 

 Having found means to place a stratum of alcohol on With alcohol 



the water contained in the glass, so that the two liquids *^^ 5®^^" ^° 

 , & 3 ^ not float, 



appeared as distinct from each other, as when the upper 

 stratum was oil, I poured from a very small height a small 

 quantity of the very fine powder of tin upon the al- 

 cohol. 



This powder totally descended through the alcohol, and 

 the water, without giving the smallest indication of its 

 having been subjected to any resistance at the surface of 

 the latter fluid. 



Though this last surface appeared very distinctly to the 

 eye, yo^t judging from the manner in which the metallic 

 powder descended to the bottom of the glass, I am dis- 

 posed to think that it had no existence ; and in fact it is 

 probable that it was destroyed by the chemical action of 

 the alcohol in contact with the water. 



In order to examine more accurately the kind of film 

 which is formed at the surface of the water, I made the 

 following experiment : 



EXPERIMENT V. 



In a cylindrical glass with a solid foot, the diameter when the first 

 of which was fourteen lines or about an inch and a half experiment is 

 English, and ten inches in height, I poured very limpid ^L^oTsmai 

 water to the height of nine inches, and on the water I diameter, the 

 placed a stratum of ether, three lines or twelfths of an t^^^khiTof 



Inch 



