442 Dr. Watt on the Phancmena 



margin or fhore. But, according to my fup- 

 poficion, when any quantity of oil is poured 

 upon water, being lighter than that water, it 

 will necefiarily fwim upon it j and by the com- 

 mon laws of hydioftatics, it will immediately 

 tend to form an exad horizontal level : in doing 

 this, it will fpread upon the furface of the water, 

 till it forms a film almofl inconceivably thin, 

 and peifeftly unbroken, on account folely of 

 the ftrong attradlion of the particles of oil to 

 each other. 



I will clofe thefe obfervations with a few 

 remarks on the finguhir fadt, to which I have 

 juft now alluded. 



The world is difpofed to call this a difcovery 

 of Dr. Franklin ; but in that they are much 

 miftaken. He himfclf does not pretend to 

 claim the difcovery of this faclj nay, he produces 

 many proofs, that it was well known and applied 

 long ago. It requires, however, very frequently 

 the name of an ingenious man to perfuadc us 

 to take notice of a very common phsenomenon } 

 for this fingular operation of oil, though it ex- 

 cited fo much attention, as a novelty, when 

 introduced by Dr. Franklin^ was long ago re- 

 marked by naiuralifts much lefs informed than 

 thofe of modern times. Of this I fhall mention 

 a few inflances, in addition to thofe alluded 

 to by Dr. Franklin. Fliny fays of the fea, •* Anne 

 Oleo tranquillari, & ob id urinantes ore fpargere; 



quoniara 



