18 On Camphor Pulsations. 



The vessel selected for the above experiment was a conical 

 foot glass, four inches in diameter at the mouth. I have lately 

 had occasion to show the experiment in a very shallow vessel 

 with a flat bottom, and have obtained some additional results, 

 which may be interesting to your readers. Two vessels were 

 emplo} T ed, one a glass saucer, used for holding a glass flower 

 pot; it is five inches in diameter, and slightly raised at the 

 bottom. The other a flat dessert dish of uncut glass, 6^ inches 

 in diameter. The phenomena are best seen in glass vessels, 

 but a dinner or dessert plate will answer the purpose. The 

 glass saucer was made quite clean, two ounces of water were 

 poured into it, and a stick of camphor, 1^ inch long, and about 

 \ inch square, with a square base, mounted in forceps, was 

 brought down so as to touch the bottom in the centre of the 

 slightly convex swelling. No sooner does the camphor touch 

 the water than a series of vibrations sets in, agitating the 

 whole surface of the water with rapid pulsations, so rapid, 

 indeed, that it is scarcely possible to count them. I have, 

 however, made out as many as 260 per miuute.* In t^his small 

 quantity of water solution takes place rapidly, and the water 

 becomes saturated -, hence the pulsations gradually diminish to 

 00 or 80 beats per minute, when solution and evaporation may 

 be considered as pretty well balancing each other. I have 

 even known the pulsations to sink down to 8 or 10 per minute, 

 and to subside altogether when the air became damp from wet 

 weather. On changing the water the pulsations will set in 

 again, but not with the maximum rapidity, unless in a dry air. 

 There is one condition connected with the complete success 

 of this experiment which I was some time in discovering. It 



this. The stick of camphor must be cut in the direction of 

 the grain or cleavage of the camphor, but not across it or 

 obliquely to it. On holding a piece of camphor up to the light 

 it will soon be seen in what direction the cut is to be made, 



d when the piece lias been nicely trimmed and mounted in 

 its forceps, and brought down so as to touch the bottom of the 

 ion appears to be this: — The water rises by capil- 

 q some Avay up the camphor, and detaches a 

 i of its substance, which is then Bpread out in the form 

 of a film over the surface of the water by the attraction of 

 adhesion, am'; ■ disposed of by solution and evaporation, 



afti lannert itaal oils. As the film is being detached, 



it repels the wale:- from the camphor, and produces a depression 

 ail round the stick; the water recovers itself by a 

 bound, capillarity again comes into play, another film is de- 

 tached, and matters proceed as before; the result being a series 



rapid pulsation* are best seen on the larger surface of the water in 

 t dish. 



