122 [November, 1841. 



this jar and a rapid motion is given to the latter, the liquid hy 

 degrees acquires the rotary velocity, and by the effect of centrifu- 

 gal force is compelled to rise round the inside of the jar. If the 

 velocity be sufficient, the liquid may be made to rise to the very 

 top of the jar and be thrown out. 



If two liquids of different specific gravities and incapable of 

 chemical action on each other, be placed within the jar, the rota- 

 tion of the glass may give to the different liquids corresponding 

 velocities of rotation, but these will be acquired in times varying 

 with the adhesiveness of the liquid to the glass. 



This diversity in the times of acquiring the same velocity as the 

 containing vessel, gives rise to some apparent anomalies, while the 

 speed is either increasing or diminishing. If oil and spirit of tur- 

 pentine be placed in the cylinder, the former at the bottom, the 

 surface of separation is more concave upward than the upper surface 

 of the turpentine, because the oil is more adhesive than the spirits 

 of turpentine : but placing alcohol below the spirits of turpentine, 

 the latter becomes the more adhesive liquid and acquires the velo- 

 city of revolution of the jar sooner than the other, whence it will, 

 by its superior centrifugal force, be urged downward as well a 

 upward, from its original level while at rest. The more adhesive 

 liquid in this case constitutes a double concave lens. The same is 

 produced when water, oil and alcohol are made to revolve in the 

 same jar, the oil occupying the middle stratum in a state of rest, 

 forms, at first and while the velocity is increasing, a concave sur- 

 face both above and below, but when the speed of the revolution of 

 the jar is slackened, it is by its superior adhesiveness sooner brought 

 to rest than the other two liquids ; these will therefore, by con- 

 tinuing their centrifugal force after that of the oil has ceased, cause 

 the latter to assume a double convex form. 



Prof. Johnson referred to some statements relative to experiments 

 of this nature sometime since made in Paris, in which it was de- 

 clared, that the " chemical affinities''' of the liquids were the cause 

 of these apparent anomalies ; and that attempts had been made to 

 deduce from experiments of this nature " a mechanical measure of 

 chemical affinity." With that species of attraction he proved that 

 the results could have no connexion. 



