418 Mr. C. Tomlinson on the Motions of Camphor 



ered to the bottom of the vessel, the water rises by capillary 

 attraction some way up the stick and detaches a portion of 

 its substance, which is then spread out as a film by surface ad- 

 hesion and disposed of by solution and evaporation. As the film 

 is being detached, it repels the water from the camphor and pro- 

 duces a depression of surface all round the stick; the water 

 recovers itself, capillarity again comes into play, another film is 

 detached, and matters proceed as before — the result being a series 

 of pulsations or waves which rise up so that at length their crest 

 may be one, two, or three tenths of an inch above the general 

 surface of the water. The variations in height are marked by a 

 series of curved grooves or ripple-lines on the sides of the cam- 

 phor, which gradually exchanges its dull translucent appearance 

 for a bright transparent one, showing that the water has pene- 

 trated it. In the meantime an incision is made in the camphor, 

 which goes on increasing as successive films are detached, until 

 the stick is cut through and the submerged portion rises to the 

 surface and commences a series of gyrations on its own account. 



27. As, in the case of small fragments of camphor rotating on 

 the surface of water* the motions are stopped if the surface be 

 touched with a fatty oil, so these pulsations are immediately 

 arrested if the water be touched with a drop of any substance 

 which forms a film and arrests evaporation. The point of a pin 

 dipped into olive-oil and brought into contact with the water at 

 once stopped the lycopodium currents (25) ; a second contact 

 stopped the pulsations (26) . So also if a body be added to the 

 water that satisfies its adhesion so as to stop the solution of the 

 camphor, the pulsations are arrested. Thus a drop of oil of 

 camphor stops the pulsations by depriving the water of the 

 power of dissolving camphor ; a drop of olive-oil stops the pul- 

 sations by preventing evaporation ; but a drop of oil of bitter 

 almonds, which speedily evaporates, allows the pulsations to go 

 on after a slight interruption. Turpentine and bodies that 

 leave a permanent film stop the pulsations ; but ether, alcohol, 

 benzole, bisulphide of carbon, caustic potash, and sal-ammoniac 

 allow r them to go on. A bit of sponge tied to the end of a glass 

 rodj dipped into ether and held near the camphor, will hold up 

 the w r ave of water against the camphor for some time. A drop 

 of benzole does not stop the pulsations ; but it makes them less 

 rapid. The pulsations go on in a solution of caustic potash and 

 in one of sal-ammoniac. The pulsations and rotations of camphor 

 are not arrested by the addition of acids to the water, including 

 butyric acid. Camphor even rotates on the surface of acetic acid. 



28. In 1863 1 obtained a result 30 which seemed to place the es- 

 sential oils in a new light with respect to the surface of water. It 



so Phil. Mag. September 1863. 



