322 Mr. A. Trevelyan on the Vibration of heated Metals. 



Practical Chemistry. Having mentioned the circumstance and 

 shown him the experiments, he informed me that the fact was 

 new, and recommended me to make further experiments, and 

 prepare a paper on the subject for the Royal Society of Edin- 

 burgh. I took his advice, and during the winter session had 

 the honour of having two papers read before that Society, 

 which were illustrated by experiments. 



Since that time I have made numerous additional experi- 

 ments, and have succeeded in obtaining vibration with most 

 metals, many of which I failed with previously, from the ap- 

 paratus not being sufficiently delicate. 



On the opposite page is a Table of the different metals in 

 which I have observed vibration. 



The experiments were repeated several times before I was 

 satisfied with the results. 



I have not yet observed any effect with bismuth, although 



1 have with pale solder, which is an alloy of that metal. 



The gold was in too small a piece to try cold, with the hot 

 bar placed on it. The results with it and with platinum 

 would probably have been more numerous, if I could have 

 obtained better-shaped pieces of those metals. 



Bars of tin, lead, bismuth, antimony, block tin, solder, 

 tin-solder and pale solder, produced no effect, when heated 

 and placed on cool blocks, or rings, of all the different metals 

 mentioned in the Table. 



Cold bars of lead, bell-metal, tin-solder and pale solder, 

 when placed on heated iron or brass, produced vibration and 

 tone. The cold lead block, placed on the heated polished bar 

 of a fire-grate, sounds loudly, and vibrates rapidly. 



The vibration continues in the exhausted receiver of an air- 

 pump. 



The bars begin to vibrate on lead at a temperature below 

 212° Fahr., but on harder metals they require a higher tem- 

 perature. 



A cool brass bar, 5 inches long, 2 inches wide and gths of 

 an inch thick, placed on a cool lead cylinder \ an inch thick, 



2 inches in height and 4£ inches in diameter, with a spirit- 

 lamp placed under the bar, produced vibration and tone in 

 6 minutes 15 seconds, and continued sounding for 5 hours and 

 55 minutes : when I removed the lamp, it ceased vibrating in 

 6 minutes, but might probably be continued, by the continued 

 application of the lamp, for any length of time. The block 

 had arrived at so high a degree of temperature, that it was too 

 hot to hold with the naked hand : the vibration was only kept 

 up by the brass bar being so superior to lead in its power of 

 conducting caloric. From the small size of the bar, it soon 

 fell to the same temperature as the lead, and then of course 

 the vibration ceased. 



