1835.] Observations on Visible Vibration. 365 



adding about an equal bulk of mercury the temperature 

 fell to 190°, when both oil and mercury undulated a little, 

 but all motion ceased in a minute or two as the tempera- 

 ture fell. 



30. A compound of castor oil and alcohol did not vibrate. 



31. Rape oil, at the ordinary temperature of the atmos- 

 phere shews not the slightest indication of vibration ; nor 

 indeed, do any of the oils at ordinary temperatures (23) 

 but rape oil at 310° undulated at the circumference. On 

 adding about an equal bulk of mercury, the temperature 

 fell to about 140°, and both fluids undulated at the circum- 

 ference. A needle on the mercury beneath the oil was 

 quite unaffected. At 126° not the slightest motion was ap- 

 parent in the oil. 



32. Linseed oil at 367° undulates freely and swims nar- 

 row slips of writing paper round in the direction of the 

 finger. The paper, however, soon sinks, shewing the small 

 sp. gr. of the heated oil. 



33. Sulphuric acid, (sp. gr. 1*839) was heated to 239°, 

 when it vibrated almost as readily as water. After a short 

 time, about an equal bulk of mercury was added and the 

 temperature fell to 95°, but neither fluid vibrated. 



34. The muriatic, nitric, acetic, and pyro-ligneous acids 

 are good vibrators, the two latter even better than water. 

 A narrow slip of writing paper placed on the surface of 

 either of the two latter, is borne round quickly in the direc- 

 tion of the finger 



35. A mixture of sulphuric acid four parts, and alcohol 

 one part, vibrates well. 



36. The saponaceous compound, procured by adding 

 liquor ammoniae to oil and water, does not vibrate. 



37. I have already noticed the proposition of Chladni, 

 (5) that in order to produce a musical note from a glass 

 containing a liquid, that both glass and liquid must vibrate 

 together in unison as a system. Now in the above experi- 

 ments, whether the liquids that I used vibrated or not, I 

 always procured a full, clear, musical note from the glass ; 

 from the densest oil that I employed, which was castor oil, to 



the most limpid sperm oil. I have even found, contrary to 

 the general and received opinion, that a glass containing a 

 liquid in a state of active effervescence, will yield a full and 



