364 Mr. Tomlinsons Experiments and [Mat 



oleaginous substances are employed instead of mercury, 

 except that they do not vibrate. 



23. I now proceed to notice the effects of this method of 

 vibration on other fluids, and their effects on mercury. 

 The fixed oils and sulphuric acid, I find, will not vibrate, and 

 when poured on the surface of mercury they entirely prevent 

 its vibration. 



24. I attribute this preventive effect to the consistency 

 of those fluids, for muriatic acid vibrated and permitted the 

 mercury to vibrate. Nitric acid also vibrated, and its de- 

 composition seemed retarded by the vibration. I could not 

 distinguish whether the mercury vibrated ; but when two 

 drachms of acid were diluted with the same bulk of water, 

 both dilute acid and mercury vibrated readily. 



25. When oil is poured on the surface of the mercury, 

 the vibration of the latter may be restored by the addition 

 of water ; the oil rising to the surface of that fluid allows 

 the mercury to vibrate. If, however, oil of cloves be em- 

 ployed, or any oil of greater sp. gr. than water, the water 

 will remain on the surface and vibrate, while the two strata 

 of fluids below remain quiescent; but, if sulphuric acid be 

 diluted with about its own bulk of water, it will vibrate and 

 allow the mercury to vibrate also. 



26. At a temperature of 238° olive oil vibrates, or rather 

 undulates at or near its circumference, but all motion soon 

 ceases as the temperature falls. 



27. Sperm oil at 340° vibrates as readily as water ; its 

 ready vibration decreases, of course, as the temperature 

 falls, and at about 180° its vibration ceases. 



28. Sperm oil at 300° poured on mercury at the atmos- 

 pheric temperature vibrates, and allows the mercury to vibrate 

 as effectually as if it were but water. The temperature of the 

 oil rapidly decreases, in consequence of absorption of heat 

 by the mercury and radiation, but the most singular part of 

 this experiment is, that after the oil has ceased to vibrate, 

 the mercury vibrates readily, and turns the oil round at a 

 temperature so low as 80°, and a needle placed on the sur- 

 face of the mercury beneath the oil, turns slowly round in 

 the direction of the finger, as also small shot at the cir- 

 cumference. 



29. Castor oil at 368° vibrates, but not readily. On 



