x68 MOTION of Small Liihted WICKS 



ly into contacft, there was foon produced a fiiperficial ftream or 

 efflux from the iron in all diredions, which cleared the face of 

 the oil from the charcoal duft, in a wider and a wider circle, till 

 at laft the whole particles were crowded together at the confines 

 of the bafon. 



When the oil in this experiment was fhallow, having gold 

 leaf beat into very minute parts mixed with it, an oppofite 

 ftream was obferved below, fetting in towards the poker in all 

 directions, and then rifing upwards. But this general tendency 

 of all the parts of the fluid of moving in queft of an equili- 

 brium, is illuftrated in a very entertaining manner as follows : 

 Into a tea-cup or punch-glafs, nearly filled with pure water, pour 

 a defert fpoonful of very clean falad oil, with minute particles 

 of gold leaf in it. If the water be cold, the oil, when poured 

 on at the centre, leifurely and continuedly, will reft upon the 

 furface in the form of a lens, and remain infulated or equidi- 

 ftant from the fides of the veflel. A little lamp, when put up- 

 on this lens of oil, and lighted, will fail and circulate as larger 

 ones do in the bafon. If it be now made to ftand ftill, it is 

 very amufing to obferve the minute particles of the gold per- 

 petually thrown out brilkly at the ftern in the fuperficial cur- 

 rent, whilft the particles in the fund of the lens creep in all di- 

 rections towards the lamp, and at laft rife up under the bafe 

 towards the flame, as the great centre of attradion, till they are 

 caught by the retreating fuperficial ftream, in which they ra- 

 pidly trend off to fome diftanee, when again they fink to renew, 

 the circulation. 



When a patch of paper, or a wafer, or fuch light body, 

 fwims upon the oil in the bafi^n, the point of a hot iron held 

 near to it makes it flit its place, and move away by a feeming 

 repulfion ; but, in reality, by the heat generating a fuperficial 

 ftream, flowing from the iron in. all diredions. 



Agai>?, 



