54 VISCIDITY OF water; 



EXPERIMENT III. 



The same ex- HaTing poured a large drop of mercury into a china 

 S^alTgl^obulM P^^^' I broke it into a great number of small spherules, 

 of mercury. In order to take up and convey these small spherules 



one by one, I made a small tool or shovel out of a piece 

 of brass wire, five inches long and about one twentieth of 

 an inch in diameter, bended to a right angle at one of its 

 extremities. This bended part was about a quarter of an 

 inch long, and was hammered flat, sharpened, and made 

 a little concave. 



By means of this tool I took up a small spherule of 

 mercury, about one sixtieth of an inch diameter, which I 

 carefully conveyed into the stratum of ether to the distance 

 of about one twentieth of an inch from the surface of tli# 

 water beneath ; and there, by a little inclination of the in- 

 strument, I caused the spherule of mercury to roll gently 

 on the surface of the water. 



The spherule descended to that surface and there re- 

 mained floathig. 

 The floating When the eye was placed lower than the surface of the 



fo^rmed a'kLd "^^^^^^^j ^"^ *be sphefule was observed by looking up- 

 of bag or cavity wards through the glass ; it appeared suspended in a kind 



in the surface of bag, a little below the level of the surface. 

 of the water. ,, 



Having placed a second spherule of mercury on the sur- 

 face of the water, it immediately moved towards the for- 

 mer, and approaching it with an .accelerated motion, fell 

 down into the same cavity, which then became longer ; 

 but the two spiicrules did not unite. 



Having placed a third spherule on the surface of the 

 water, it joined the two others, but the weight of these 

 three spherules together being too great to be supported 

 by the kind of pellicle which is formed at the surface of 

 the water, the bag was broken, and the spherules descend- 

 ed through the water to the bottom of the vessel. 

 — .whichbreaks When the experiment was made with a spherule of 

 when the body ,. , , , i_ ^ xi i- x- xu re 



is too heavy, mercury, a little larger, namely about the lortietn or nf- 



tieth of an inch, it never failed to break the pellicle of (he 

 water, and to descend through that liquid to the bottom 

 of the glass. But when the viscidity of the water was in- 

 creased by dissolving a small quantity of gum arable in it^ 

 sfill larger spherules of mercury were supported at the 



surface of the liquid. 



A spherule 



