WATEll HEATED BY FRICTION. 113 



I do not intend by these gradations to confound the two 

 stones: their elements, and their external characters, con- 

 sidered in the extremes, are sufRciently marked, to consti- 

 tute distinct species. I would only remark, that they have 

 shades of resemblance, which tend to confirm the results 

 of analysis. 



VII. 



Remarkable Fact of an Inei^ease of Temperature produced in 

 Water by Agitation. In a Letter from, Joseph Readb, 

 M.D. 



To Mr. NICHOLSON. 



SIR, Cork, May 8, 180S. 



S 



INCE my communication on the increased capacity of 

 water, I have been engaged with some experiments on heat 

 excited by friction, one of which I beg leave to communir 

 cate through the medium of your Philosophical Journal, 

 and hope it may not be esteemed uninteresting. I shall 

 confine myself to a concise recital of the experiment, which 

 if confirmed, is in direct contradiction to received opinion, 

 that the agitation or friction of fluids cannot excite sensible 

 beat. 



Experiment. 

 The temperature of the apartment being 40% half a pint Water at 40* 



of water, at a similar heat, was poured into a tin bottle- "^"^^ ^° ^^° ^y 



1 1-1 /. 1 • 1 • , agitation in a 



shaped vessel; mto the aperture ot which was inserted a dosed tin ves- 



thermorneter, surrounded with chamois leather, and made sel. 

 to fit accurately, with its bulb nearly in the axis. After 

 briskly agitating the vessel for a few minutes, to my ex- 

 treme surprise 1 found the temperature of the water rose 8 

 degrees; and even after the apparatus was uncovered and 

 laid at rest on the table, the water continued to rise for se- 

 veral minutes ; proving the origin of the heat to be inherent 

 in the fluid, and independent of any external causes. Anx- 

 ious however to obviate every source of fallacy or objection. 

 Vol. XX — June, 1808. I I prevented 



